Improve `typing.py` docstrings

[AlexWaygood]

The docstrings in typing.py could do with a spring clean. As well as several small grammatical errors, there's also several details which are out of date; very inconsistent indentation in code examples; and numerous other small things that could be improved.

Linked PRs

• gh-105286: Improve typing.py docstrings #105287
• [3.12] gh-105286: Improve typing.py docstrings (#105287) #105319
• [3.11] gh-105286: Improve typing.py docstrings (#105287) #105322
• gh-105286: Further improvements to typing.py docstrings #105363
• [3.12] gh-105286: Further improvements to typing.py docstrings (GH-105363) #105416
• [3.11] gh-105286: Further improvements to typing.py docstrings (GH-105363) #105417