[feature] improve readability of argument value

[HerringtonDarkholme]

⭐ Suggestion

This is how ripgrep prints

        --color <WHEN>
            This flag controls when to use colors. The default setting is 'auto', which
            means ripgrep will try to guess when to use colors. For example, if ripgrep is
            printing to a terminal, then it will use colors, but if it is redirected to a
            file or a pipe, then it will suppress color output. ripgrep will suppress color
            output in some other circumstances as well. For example, if the TERM
            environment variable is not set or set to 'dumb', then ripgrep will not use
            colors.

This is how ast-grep outputs

      --color <COLOR>
          Controls output color

          [default: auto]

          Possible values:
          - auto:   Try to use colors, but don't force the issue. If the output is piped to another program, or the console isn't available on Windows, or if TERM=dumb, or if `NO_COLOR` is defined, for example, then don't use colors
          - always: Try very hard to emit colors. This includes emitting ANSI colors on Windows if the console API is unavailable (not implemented yet)
          - ansi:   Ansi is like Always, except it never tries to use anything other than emitting ANSI color codes
          - never:  Never emit colors

💻 Use Cases

• Change the description
• Make the value placeholder more descriptive