gh-101100: Fix sphinx warnings in library/asyncio-eventloop.rst

[sobolevn]

Before:

/Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:512: WARNING: py:const reference target not found: socket.TCP_NODELAY /Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:581: WARNING: py:const reference target not found: socket.SO_REUSEPORT /Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:609: WARNING: py:const reference target not found: sockets.SO_REUSEADDR /Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:617: WARNING: py:const reference target not found: sockets.SO_REUSEPORT /Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:702: WARNING: py:const reference target not found: socket.AF_UNSPEC /Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:758: WARNING: py:const reference target not found: socket.TCP_NODELAY /Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:1891: WARNING: py:data reference target not found: SIGINT /Users/sobolev/Desktop/cpython/Doc/library/asyncio-eventloop.rst:1891: WARNING: py:data reference target not found: SIGTERM 

So, what I did?

1. I've added unix-constants reference, better name is appreciated, because not all constants under TCP_* are explicitly documented. I don't think that there's clean a way to do that
2. I've also documented AF_UNSPEC, because it is rather special. I took the wording from https://man7.org/linux/man-pages/man3/getaddrinfo.3.html

• Issue: Fix all Sphinx reference warnings in the documentation #101100

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📚 Documentation preview 📚: https://cpython-previews--111222.org.readthedocs.build/

[miss-islington-app]

Thanks @sobolevn for the PR, and @willingc for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[bedevere-app]

GH-111469 is a backport of this pull request to the 3.12 branch.

[bedevere-app]

GH-111470 is a backport of this pull request to the 3.11 branch.