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-command/src/network/url/encode.rs

@@ -20,7 +20,7 @@ impl Command for SubCommand {
             .input_output_types(vec![(Type::String, Type::String)])
             .vectorizes_over_list(true)
             .switch(
-            "all", 
+            "all",
             "encode all non-alphanumeric chars including `/`, `.`, `:`",
             Some('a'))
             .rest(
@@ -32,7 +32,7 @@ impl Command for SubCommand {
     }
 
     fn usage(&self) -> &str {
-        "Converts a string to a percent encoded web safe string"
+        "Converts a string to a percent encoded web safe string."
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-command/src/network/url/join.rs

@@ -19,7 +19,7 @@ impl Command for SubCommand {
     }
 
     fn usage(&self) -> &str {
-        "Converts a record to url"
+        "Converts a record to url."
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-command/src/network/url/parse.rs

@@ -27,7 +27,7 @@ impl Command for SubCommand {
     }
 
     fn usage(&self) -> &str {
-        "Parses a url"
+        "Parses a url."
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-command/src/network/url/url_.rs

@@ -20,7 +20,7 @@ impl Command for Url {
     }
 
     fn usage(&self) -> &str {
-        "Various commands for working with URLs"
+        "Various commands for working with URLs."
     }
 
     fn extra_usage(&self) -> &str {