[3.12] gh-117114: Update availability and source code link in os.path.rst

[nineteendo]

I added a link to Lib/genericpath.py in the documentation of os.path (and removed the redundant availability notes) in this pull request: #117115, but this wasn't backported.

Note: the other changes in this pull request are NOT being backported.

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📚 Documentation preview 📚: https://cpython-previews--117756.org.readthedocs.build/

• Issue: Add isdevdrive to posixpath #117114

[nineteendo]

@erlend-aasland, could you add the skip-issue label? Or must I first make an issue for this?

[erlend-aasland]

@erlend-aasland, could you add the skip-issue label? Or must I first make an issue for this?

AFAICS, this belongs to gh-117114.

[erlend-aasland]

Are you sure about those availability adjustments?

[nineteendo]

Yeah, when a function is defined in both Lib/ntpath.py & Lib/posixpath.py, it's available on all platforms.

I also think I know why these availability notes are here: these functions weren't available in macpath, and the notes weren't removed together with it: d7538dd.

[nineteendo]

@zooba, thoughts?

[nineteendo]

@AlexWaygood, do you have an opinion on this?

[zooba]

I also think I know why these availability notes are here: these functions weren't available in macpath, and the notes weren't removed together with it

That and probably a few were only available on one, and then when we added the other we added to the list rather than removing the list.

This looks good to me.