Further improve docs for typing.Annotated

[AlexWaygood]

A significant followup PR to #105365.

• Snappier first sentence. Use shorter sentences and shorter paragraphs throughout.
• Describe it as a "typing form", not a "type" -- Annotated isn't a type, you can't use it directly as a type annotation.
• Add links to other functions where they're being cross-referenced.
• Use the term "metadata elements" to describe the metadata in the __metadata__ attribute at runtime, rather than "annotations" or "types", which were being used before.
• Use PEP-695 syntax for more examples.
• Don't use the .. attribute:: directive for the __metadata__ attribute. It's not being rendered correctly -- Sphinx thinks it's a module attribute rather than an attribute of Annotated[X, "foo"]. Current rendering. This is because we don't mark up Annotated as a class in the docs. (It actually is a class at runtime, at the moment, but that's an implementation detail. I don't think we should mark it as a class in the docs.)
• Add a note to the docs that is currently only present in the docstring about how an Annotated type cannot be made generic over a TypeVarTuple.
• State more clearly that the default of get_type_hints is to strip metadata from Annotated annotations, and add an example.
• Move the link to the PEP down to the bottom as a .. seealso:: box.
• There was a sentence that described "calling" Annotated, which was incorrect: you subscript Annotated, you don't call it.

---

📚 Documentation preview 📚: https://cpython-previews--105498.org.readthedocs.build/

[AlexWaygood]

@erlend-aasland, it would be great to get some non-typing-expert eyes on this, if you have the time to take a look :)

[AlexWaygood]

Old: https://docs.python.org/3/library/typing.html#typing.Annotated

New: https://cpython-previews--105498.org.readthedocs.build/en/105498/library/typing.html#typing.Annotated

[erlend-aasland]

@AlexWaygood, I'll have a look!

[JelleZijlstra]

This looks misindented, as it's indented by one space less than the next paragraph.

[AlexWaygood]

Hmm, it seems the bulleted list is inconsistent about whether there should be one or two spaces after a bullet point.

[AlexWaygood]

I decided it was probably the next paragraph that had the wrong indentation -- does it look better after 2cd15fe?

[JelleZijlstra]

Looks good, one formatting nit

[erlend-aasland]

The new text is definitely easier to read for a typing newbie like me. Thanks!

[AlexWaygood]

The new text is definitely easier to read for a typing newbie like me. Thanks!

Great to hear!

[JelleZijlstra]

Thanks, looks good!

[miss-islington]

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

[bedevere-bot]

GH-105503 is a backport of this pull request to the 3.12 branch.

[bedevere-bot]

GH-105504 is a backport of this pull request to the 3.11 branch.