gh-107801: Improve the accuracy of io.TextIOWrapper.seek docs

[erlend-aasland]

Clearly document the supported seek() operations:

• Rewind to the start of the stream
• Restore a previous strema position (given by tell())
• Fast-forward to the end of the stream

• Issue: Docs and docstrings for io.*.seek are inconsistent #107801

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📚 Documentation preview 📚: https://cpython-previews--107933.org.readthedocs.build/

[AA-Turner]

I like this presentational approach, I think it's a significant improvement over the status quo!

A

[erlend-aasland]

Thanks for the reviews, Antoine and Adam; highly appreciated.

I think we're almost there, but I don't like the repetition in the summary sentence. I thought of changing it to "Set and return ...", but perhaps that is not accurate enough.

[erlend-aasland]

It seems the review comments of @pitrou have been addressed. I'll land this next week.

[miss-islington]

Thanks @erlend-aasland for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[miss-islington]

Sorry, @erlend-aasland, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 7f87ebbc3f52680c939791f397b9a478edf0c8d4 3.12

[miss-islington]

Sorry, @erlend-aasland, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 7f87ebbc3f52680c939791f397b9a478edf0c8d4 3.11

[erlend-aasland]

I will create a follow-up PR for documenting tell().

[bedevere-bot]

GH-108262 is a backport of this pull request to the 3.12 branch.

[bedevere-bot]

GH-108264 is a backport of this pull request to the 3.11 branch.