gh-131417: Mention asyncio Future and Task in docs for generic classes list

[asvetlov]

• Issue: stdtypes don't mention asyncio generic classes #131417

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📚 Documentation preview 📚: https://cpython-previews--131422.org.readthedocs.build/

[picnixz]

I see that those classes are generic since 2022. Are they fully generic (namely, both C and Python implementation?). If so, we can backport the docs up to 3.12.

[asvetlov]

They are fully generic, yes. Let's backport

[picnixz]

Tip: The 3.x labels are used on issues to target bugs in specific versions (I personally don't add version tags if the bug was present since the beginning or I just amend the title; it lets me avoid having to re-triage them in 5 years). The "needs backports" labels are added on PRs to tell the bot to make the bps later.

[asvetlov]

Thanks, @picnixz