Add scope descriptions to plugin READMEs

[Andre601]

Right now, a README of a plugin may have something alongside this in their "Supported specifications" section:

🔑 (scopeless) read:org (optional) read:user (optional) read:packages (optional) repo (optional)

While it shows what is and isn't required, does it not really tell you what each scope's purpose here would be.
What would read:org achieve for this plugin?
If I want to have repos of another org listed, do I only need a token with read:org, one with repo or both?

So, it could be a good idea to add a section within the README file to explain any listed scope and their purpose when used.
It would help reduce general confusion, especially for people who have no understanding of tokens, their scope and what is and isn't required for their needs.

[lowlighter]

It's partially documented here:

metrics/.github/readme/partials/documentation/setup/action.md

Lines 25 to 32 in c895cb0

	A a general rule, the following scopes may be required:
	- `public_repo` for some plugins
	- `read:org` for all organizations related metrics
	- `repo` for all private repositories related metrics
	- `read:user` for some private repositories related metrics
	- `read:packages` for some packages related metrics
	- `read:project` for some projects related metrics
	- `gist` for publishing renders to gists instead of a repository

But it's true that it's still pretty vague. The optional scopes you listed are most of the time appended automatically by the docs generator
Things is that as far as I know, GitHub doesn't provide detailed access of each scope

Like I'm pretty confident that anything related to org requires read:org and anything with private data requires repo scopes.
For other it's a bit more blurry, like not sure if read:packages is actually used somewhere, read:project is required for new GitHub projects, but the legacy ones are requiring the public_repo scope, and for read:user I'm not sure what this covers (I remember it being used for 1 or 2 specific stats but not sure which ones actually)