Documentation Link

https://matplotlib.org/devdocs/devel/api_changes.html#deprecation

Problem

The deprecation docs are fairly terse in terms of which decorator gets applied where/how.

Suggested improvement

@QuLogic had a really nice write up with examples of how to do deprecation in #26865 and I think it'd be great to fold that into our deprecation guide.

Especially if deprecation is gonna be a standing sprint/good first issue, it's nice to be able to point to a page in docs and not have it mixed up w/ issue information;.