Add version directives to ast docs

[hauntsaninja]

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📚 Documentation preview 📚: https://cpython-previews--108788.org.readthedocs.build/

[JelleZijlstra]

The versionadded directives for a bunch of the match nodes are rendered within the code blocks: https://cpython-previews--108788.org.readthedocs.build/en/108788/library/ast.html#ast.MatchAs

I didn't add these initially because other recently added objects didn't have them. Not sure if there's a reason behind that, but it seems useful to add the directives.

You might also want to add 3.8 for NamedExpr, which incidentally is misindented (https://docs.python.org/3.10/library/ast.html#ast.NamedExpr).

[bedevere-bot]

When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.

[hauntsaninja]

Thank you! (I have made the requested changes; please review again)

[bedevere-bot]

Thanks for making the requested changes!

@JelleZijlstra: please review the changes made to this pull request.

[JelleZijlstra]

The build preview didn't update but I built locally and everything looks fine now, thanks!

We'll have to do a manual backport for 3.11.

[hugovk]

Aside: maybe the build preview was slow to upload or cached or something, here's the new versionadded above the "Subscripting" header:

https://cpython-previews--108788.org.readthedocs.build/en/108788/library/ast.html#subscripting

[miss-islington]

Thanks @hauntsaninja for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[bedevere-bot]

GH-109106 is a backport of this pull request to the 3.12 branch.