gh-110383: Document `socket.makefile()` accepts combined modes

[squeakyboots]

ref: #110383 ref: https://mail.python.org/archives/list/[email protected]/thread/3VGLA6Q6QDYB7XIAHFIRAVW4TQSEAZGA/

• Issue: gh-110383

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📚 Documentation preview 📚: https://cpython-previews--119150.org.readthedocs.build/

[ghost]

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[miss-islington-app[bot]]

Thanks @squeakyboots for the PR, and @erlend-aasland for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13. 🐍🍒⛏🤖

[bedevere-app[bot]]

GH-119324 is a backport of this pull request to the 3.13 branch.

[bedevere-app[bot]]

GH-119325 is a backport of this pull request to the 3.12 branch.