Remove stub content/style section from CONTRIBUTING.md

[yangdanny97]

python/typing#1882 has added the stub content/style guidelines from CONTRIBUTING.md to the official typing documentation (https://typing.readthedocs.io/en/latest/guides/writing_stubs.html), so we can change the contributing guide to link to that directly.

I added a special note re: omitting docstrings from typeshed, since the official docs only discusses tradeoffs (per Jelle's recommendation in python/typing#1880 (comment))

[Avasam]

This reminds me of an old PR by @srittau and reviewed by @JelleZijlstra that went unmerged https://github.com/python/typeshed/pull/7594/files
I haven't gone through the whole thing yet, I'm just wondering if there's more sections that can be updated with a link.

[yangdanny97]

The only extra thing that PR deletes is the "Supported type system features" section. The comments mentioned linking to the issue tracker: project: feature tracker Tracks whether a typing feature can be used in typeshed stubs , but I don't quite understand @AlexWaygood 's comment

We could also consider using a meta-issue tracker to track the issue trackers.

Perhaps we can do that in a separate PR?

[Akuli]

I don't think this is a good idea.

I think CONTRIBUTING.md should be a self-contained document that you read, and then you can contribute. It should be as painless as possible to go through, so it shouldn't expect readers to follow links and read something elsewhere.

That said, "for more info see also" type of links are ok in a CONTRIBUTING.md.

[Akuli]

I think the Any trick is a good example of a "for more info, see also" kind of thing. Most contributors won't need to know about it, so it is IMO a good idea to link to it from CONTRIBUTING.md, but not explain it here.