Update/review v3 docs

[JWCook]

Follow-up from #111 (review)

Tasks:

• Add parameter documentation for all public classes and functions
• Update to Sphinx v7 if possible, and verify other doc dependencies/extensions are still working
• Verify structure and content in HTML docs:
  • Table of contents and sidebar page outlines
  • Auto-generated module docs (via sphinx-apidoc)
• Verify formatting in HTML docs:
  • Docs generated from docstrings
  • Docs generated from markdown

[JWCook]

I haven't been able to get to this yet, but I still plan to as soon as I have the time.

[andrew-cybsafe]

Given the substantial changes from 2.x to 3.x, I'd suggest that a migration guide would be very helpful. e.g.

• how do I implement @limiter.ratelimit("...", delay=True) in v3.
• RequestRate class has renamed to Rate