Uniformize usage() and extra_usage() message ending for commands helper. (#8268)

# Description

Working on uniformizing the ending messages regarding methods usage()
and extra_usage(). This is related to the issue
https://github.com/nushell/nushell/issues/5066 after discussing it with
@jntrnr

# User-Facing Changes

None.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-cmd-lang/src/core_commands/alias.rs

@@ -13,7 +13,7 @@ impl Command for Alias {
     }
 
     fn usage(&self) -> &str {
-        "Alias a command (with optional flags) to a new name"
+        "Alias a command (with optional flags) to a new name."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/break_.rs

@@ -11,7 +11,7 @@ impl Command for Break {
     }
 
     fn usage(&self) -> &str {
-        "Break a loop"
+        "Break a loop."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/commandline.rs

@@ -41,7 +41,7 @@ impl Command for Commandline {
     }
 
     fn usage(&self) -> &str {
-        "View or modify the current command line input buffer"
+        "View or modify the current command line input buffer."
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-cmd-lang/src/core_commands/continue_.rs

@@ -11,7 +11,7 @@ impl Command for Continue {
     }
 
     fn usage(&self) -> &str {
-        "Continue a loop from the next iteration"
+        "Continue a loop from the next iteration."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/def.rs

@@ -13,7 +13,7 @@ impl Command for Def {
     }
 
     fn usage(&self) -> &str {
-        "Define a custom command"
+        "Define a custom command."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/def_env.rs

@@ -13,7 +13,7 @@ impl Command for DefEnv {
     }
 
     fn usage(&self) -> &str {
-        "Define a custom command, which participates in the caller environment"
+        "Define a custom command, which participates in the caller environment."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/do_.rs

@@ -17,7 +17,7 @@ impl Command for Do {
     }
 
     fn usage(&self) -> &str {
-        "Run a closure, providing it with the pipeline input"
+        "Run a closure, providing it with the pipeline input."
     }
 
     fn signature(&self) -> Signature {

crates/nu-cmd-lang/src/core_commands/export_alias.rs

@@ -13,7 +13,7 @@ impl Command for ExportAlias {
     }
 
     fn usage(&self) -> &str {
-        "Alias a command (with optional flags) to a new name and export it from a module"
+        "Alias a command (with optional flags) to a new name and export it from a module."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/export_def.rs

@@ -13,7 +13,7 @@ impl Command for ExportDef {
     }
 
     fn usage(&self) -> &str {
-        "Define a custom command and export it from a module"
+        "Define a custom command and export it from a module."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/export_def_env.rs

@@ -13,7 +13,7 @@ impl Command for ExportDefEnv {
     }
 
     fn usage(&self) -> &str {
-        "Define a custom command that participates in the environment and export it from a module"
+        "Define a custom command that participates in the environment and export it from a module."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/export_extern.rs

@@ -11,7 +11,7 @@ impl Command for ExportExtern {
     }
 
     fn usage(&self) -> &str {
-        "Define an extern and export it from a module"
+        "Define an extern and export it from a module."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/export_use.rs

@@ -13,7 +13,7 @@ impl Command for ExportUse {
     }
 
     fn usage(&self) -> &str {
-        "Use definitions from a module and export them from this module"
+        "Use definitions from a module and export them from this module."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/extern_.rs

@@ -11,7 +11,7 @@ impl Command for Extern {
     }
 
     fn usage(&self) -> &str {
-        "Define a signature for an external command"
+        "Define a signature for an external command."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/for_.rs

@@ -14,7 +14,7 @@ impl Command for For {
     }
 
     fn usage(&self) -> &str {
-        "Loop over a range"
+        "Loop over a range."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/hide.rs

@@ -23,7 +23,7 @@ impl Command for Hide {
     }
 
     fn usage(&self) -> &str {
-        "Hide definitions in the current scope"
+        "Hide definitions in the current scope."
     }
 
     fn extra_usage(&self) -> &str {

crates/nu-cmd-lang/src/core_commands/hide_env.rs

@@ -31,7 +31,7 @@ impl Command for HideEnv {
     }
 
     fn usage(&self) -> &str {
-        "Hide environment variables in the current scope"
+        "Hide environment variables in the current scope."
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/ignore.rs

@@ -11,7 +11,7 @@ impl Command for Ignore {
     }
 
     fn usage(&self) -> &str {
-        "Ignore the output of the previous command in the pipeline"
+        "Ignore the output of the previous command in the pipeline."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/module.rs

@@ -13,7 +13,7 @@ impl Command for Module {
     }
 
     fn usage(&self) -> &str {
-        "Define a custom module"
+        "Define a custom module."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/overlay/hide.rs

@@ -14,7 +14,7 @@ impl Command for OverlayHide {
     }
 
     fn usage(&self) -> &str {
-        "Hide an active overlay"
+        "Hide an active overlay."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/overlay/list.rs

@@ -13,7 +13,7 @@ impl Command for OverlayList {
     }
 
     fn usage(&self) -> &str {
-        "List all active overlays"
+        "List all active overlays."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/overlay/new.rs

@@ -14,7 +14,7 @@ impl Command for OverlayNew {
     }
 
     fn usage(&self) -> &str {
-        "Create an empty overlay"
+        "Create an empty overlay."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/overlay/use_.rs

@@ -17,7 +17,7 @@ impl Command for OverlayUse {
     }
 
     fn usage(&self) -> &str {
-        "Use definitions from a module as an overlay"
+        "Use definitions from a module as an overlay."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/register.rs

@@ -11,7 +11,7 @@ impl Command for Register {
     }
 
     fn usage(&self) -> &str {
-        "Register a plugin"
+        "Register a plugin."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/return_.rs

@@ -14,7 +14,7 @@ impl Command for Return {
     }
 
     fn usage(&self) -> &str {
-        "Return early from a function"
+        "Return early from a function."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/try_.rs

@@ -15,7 +15,7 @@ impl Command for Try {
     }
 
     fn usage(&self) -> &str {
-        "Try to run a block, if it fails optionally run a catch block"
+        "Try to run a block, if it fails optionally run a catch block."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-cmd-lang/src/core_commands/use_.rs

@@ -14,7 +14,7 @@ impl Command for Use {
     }
 
     fn usage(&self) -> &str {
-        "Use definitions from a module"
+        "Use definitions from a module."
     }
 
     fn signature(&self) -> nu_protocol::Signature {