docs: backfill API version directives

[terminalchai]

Summary

• backfill missing version directives in the metadata API reference
• document when the iOS and Android tag helpers were added
• mark the licenses and pylock API reference pages with their introduction versions

Validation

• d:/project_contribution/.venv/Scripts/python.exe -m nox -s tests-3.11 docs
• d:/project_contribution/.venv/Scripts/python.exe -m nox -s lint (hits an existing all-files mypy failure in src/packaging/_manylinux.py under the current toolchain)
• .nox/lint/Scripts/prek.exe run --files docs/metadata.rst docs/tags.rst docs/licenses.rst docs/pylock.rst

Refs #597

[henryiii]

Don't we normally put this in the docstring? (could be / probably is done both ways, not a blocker if so).

[brettcannon]

Yep, we do.

[brettcannon]

For the autodoc bits, please put the directive in the docstring.

[brettcannon]

Yep, we do.