Change the usage misnomer to "description" (#13598)

# Description
    
The meaning of the word usage is specific to describing how a command
function is *used* and not a synonym for general description. Usage can
be used to describe the SYNOPSIS or EXAMPLES sections of a man page
where the permitted argument combinations are shown or example *uses*
are given.
Let's not confuse people and call it what it is a description.

Our `help` command already creates its own *Usage* section based on the
available arguments and doesn't refer to the description with usage.

# User-Facing Changes

`help commands` and `scope commands` will now use `description` or
`extra_description`
`usage`-> `description`
`extra_usage` -> `extra_description`

Breaking change in the plugin protocol:

In the signature record communicated with the engine.
`usage`-> `description`
`extra_usage` -> `extra_description`

The same rename also takes place for the methods on
`SimplePluginCommand` and `PluginCommand`

# Tests + Formatting
- Updated plugin protocol specific changes
# After Submitting
- [ ] update plugin protocol doc

crates/nu-cmd-extra/src/extra/bits/and.rs

@@ -37,7 +37,7 @@ impl Command for BitsAnd {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Performs bitwise and for ints or binary values."
     }
 

crates/nu-cmd-extra/src/extra/bits/bits_.rs

@@ -14,11 +14,11 @@ impl Command for Bits {
             .input_output_types(vec![(Type::Nothing, Type::String)])
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Various commands for working with bits."
     }
 
-    fn extra_usage(&self) -> &str {
+    fn extra_description(&self) -> &str {
         "You must use one of the following subcommands. Using this command as-is will only produce this help message."
     }
 

crates/nu-cmd-extra/src/extra/bits/into.rs

@@ -45,7 +45,7 @@ impl Command for BitsInto {
             .category(Category::Conversions)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert value to a binary primitive."
     }
 

crates/nu-cmd-extra/src/extra/bits/not.rs

@@ -51,7 +51,7 @@ impl Command for BitsNot {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Performs logical negation on each bit."
     }
 

crates/nu-cmd-extra/src/extra/bits/or.rs

@@ -38,7 +38,7 @@ impl Command for BitsOr {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Performs bitwise or for ints or binary values."
     }
 

crates/nu-cmd-extra/src/extra/bits/rotate_left.rs

@@ -53,7 +53,7 @@ impl Command for BitsRol {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Bitwise rotate left for ints or binary values."
     }
 

crates/nu-cmd-extra/src/extra/bits/rotate_right.rs

@@ -53,7 +53,7 @@ impl Command for BitsRor {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Bitwise rotate right for ints or binary values."
     }
 

crates/nu-cmd-extra/src/extra/bits/shift_left.rs

@@ -55,7 +55,7 @@ impl Command for BitsShl {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Bitwise shift left for ints or binary values."
     }
 

crates/nu-cmd-extra/src/extra/bits/shift_right.rs

@@ -52,7 +52,7 @@ impl Command for BitsShr {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Bitwise shift right for ints or binary values."
     }
 

crates/nu-cmd-extra/src/extra/bits/xor.rs

@@ -38,7 +38,7 @@ impl Command for BitsXor {
             .category(Category::Bits)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Performs bitwise xor for ints or binary values."
     }
 

crates/nu-cmd-extra/src/extra/conversions/fmt.rs

@@ -9,7 +9,7 @@ impl Command for Fmt {
         "fmt"
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Format a number."
     }
 

crates/nu-cmd-extra/src/extra/filters/each_while.rs

@@ -9,7 +9,7 @@ impl Command for EachWhile {
         "each while"
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Run a closure on each row of the input list until a null is found, then create a new list with the results."
     }
 

crates/nu-cmd-extra/src/extra/filters/roll/roll_.rs

@@ -18,11 +18,11 @@ impl Command for Roll {
             .input_output_types(vec![(Type::Nothing, Type::String)])
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Rolling commands for tables."
     }
 
-    fn extra_usage(&self) -> &str {
+    fn extra_description(&self) -> &str {
         "You must use one of the following subcommands. Using this command as-is will only produce this help message."
     }
 

crates/nu-cmd-extra/src/extra/filters/roll/roll_down.rs

@@ -21,7 +21,7 @@ impl Command for RollDown {
             .category(Category::Filters)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Roll table rows down."
     }
 

crates/nu-cmd-extra/src/extra/filters/roll/roll_left.rs

@@ -33,7 +33,7 @@ impl Command for RollLeft {
             .category(Category::Filters)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Roll record or table columns left."
     }
 

crates/nu-cmd-extra/src/extra/filters/roll/roll_right.rs

@@ -33,7 +33,7 @@ impl Command for RollRight {
             .category(Category::Filters)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Roll table columns right."
     }
 

crates/nu-cmd-extra/src/extra/filters/roll/roll_up.rs

@@ -21,7 +21,7 @@ impl Command for RollUp {
             .category(Category::Filters)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Roll table rows up."
     }
 

crates/nu-cmd-extra/src/extra/filters/rotate.rs

@@ -23,7 +23,7 @@ impl Command for Rotate {
             .category(Category::Filters)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Rotates a table or record clockwise (default) or counter-clockwise (use --ccw flag)."
     }
 

crates/nu-cmd-extra/src/extra/filters/update_cells.rs

@@ -27,7 +27,7 @@ impl Command for UpdateCells {
             .category(Category::Filters)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Update the table cells."
     }
 

crates/nu-cmd-extra/src/extra/formats/from/url.rs

@@ -14,7 +14,7 @@ impl Command for FromUrl {
             .category(Category::Formats)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Parse url-encoded string as a record."
     }
 

crates/nu-cmd-extra/src/extra/formats/to/html.rs

@@ -138,11 +138,11 @@ impl Command for ToHtml {
         ]
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert table into simple HTML."
     }
 
-    fn extra_usage(&self) -> &str {
+    fn extra_description(&self) -> &str {
         "Screenshots of the themes can be browsed here: https://github.com/mbadolato/iTerm2-Color-Schemes."
     }
 

crates/nu-cmd-extra/src/extra/math/arccos.rs

@@ -22,7 +22,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the arccosine of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/arccosh.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the inverse of the hyperbolic cosine function."
     }
 

crates/nu-cmd-extra/src/extra/math/arcsin.rs

@@ -22,7 +22,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the arcsine of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/arcsinh.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the inverse of the hyperbolic sine function."
     }
 

crates/nu-cmd-extra/src/extra/math/arctan.rs

@@ -22,7 +22,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the arctangent of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/arctanh.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the inverse of the hyperbolic tangent function."
     }
 

crates/nu-cmd-extra/src/extra/math/cos.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the cosine of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/cosh.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the hyperbolic cosine of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/exp.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns e raised to the power of x."
     }
 

crates/nu-cmd-extra/src/extra/math/ln.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the natural logarithm. Base: (math e)."
     }
 

crates/nu-cmd-extra/src/extra/math/sin.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the sine of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/sinh.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the hyperbolic sine of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/tan.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the tangent of the number."
     }
 

crates/nu-cmd-extra/src/extra/math/tanh.rs

@@ -21,7 +21,7 @@ impl Command for SubCommand {
             .category(Category::Math)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Returns the hyperbolic tangent of the number."
     }
 

crates/nu-cmd-extra/src/extra/platform/ansi/gradient.rs

@@ -53,7 +53,7 @@ impl Command for SubCommand {
             .category(Category::Platform)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Add a color gradient (using ANSI color codes) to the given string."
     }
 

crates/nu-cmd-extra/src/extra/strings/encode_decode/decode_hex.rs

@@ -29,7 +29,7 @@ impl Command for DecodeHex {
             .category(Category::Formats)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Hex decode a value."
     }
 

crates/nu-cmd-extra/src/extra/strings/encode_decode/encode_hex.rs

@@ -29,7 +29,7 @@ impl Command for EncodeHex {
             .category(Category::Formats)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Encode a binary value using hex."
     }
 

crates/nu-cmd-extra/src/extra/strings/format/command.rs

@@ -24,7 +24,7 @@ impl Command for FormatPattern {
             .category(Category::Strings)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Format columns into a string using a simple pattern."
     }
 

crates/nu-cmd-extra/src/extra/strings/str_/case/camel_case.rs

@@ -30,7 +30,7 @@ impl Command for SubCommand {
             .category(Category::Strings)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert a string to camelCase."
     }
 

crates/nu-cmd-extra/src/extra/strings/str_/case/kebab_case.rs

@@ -30,7 +30,7 @@ impl Command for SubCommand {
             .category(Category::Strings)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert a string to kebab-case."
     }
 

crates/nu-cmd-extra/src/extra/strings/str_/case/pascal_case.rs

@@ -30,7 +30,7 @@ impl Command for SubCommand {
             .category(Category::Strings)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert a string to PascalCase."
     }
 

crates/nu-cmd-extra/src/extra/strings/str_/case/screaming_snake_case.rs

@@ -30,7 +30,7 @@ impl Command for SubCommand {
             .category(Category::Strings)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert a string to SCREAMING_SNAKE_CASE."
     }
 

crates/nu-cmd-extra/src/extra/strings/str_/case/snake_case.rs

@@ -30,7 +30,7 @@ impl Command for SubCommand {
             .category(Category::Strings)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert a string to snake_case."
     }
 

crates/nu-cmd-extra/src/extra/strings/str_/case/str_.rs

@@ -14,11 +14,11 @@ impl Command for Str {
             .input_output_types(vec![(Type::Nothing, Type::String)])
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Various commands for working with string data."
     }
 
-    fn extra_usage(&self) -> &str {
+    fn extra_description(&self) -> &str {
         "You must use one of the following subcommands. Using this command as-is will only produce this help message."
     }
 

crates/nu-cmd-extra/src/extra/strings/str_/case/title_case.rs

@@ -30,7 +30,7 @@ impl Command for SubCommand {
             .category(Category::Strings)
     }
 
-    fn usage(&self) -> &str {
+    fn description(&self) -> &str {
         "Convert a string to Title Case."
     }