refactor: enhance the descriptions of CLI commands, closes #7572

[amrbashir]

ref: #7756

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

[FabianLars]

I like the new descriptions but why was plugin add added back?

[amrbashir]

it is just an alias for, tauri add, and I felt like it belongs under plugin subcommand as well, but could be removed, it is just a suggestion.

[FabianLars]

yeah so the reason was simply that all the other plugin commands operate on a plugin level/project while the add command operates on an actual tauri app so we felt like it could be confusing.

For ref, i think this was the discord convo about this: https://discord.com/channels/616186924390023171/986184094050316358/1138159565775569018

[amrbashir]

thanks for the context, will revert it then