Fixing missing base class in reflection docs, adding to reflection test

[pamelafox]

This PR adds "(db.Model)" to reflection docs example. I also added to the reflection test to mirror the documentation example, and I put an additional example in the docs showing default bind key.

• fixes Incorrect(?) example in documentation #1280

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code.
  - [ ] Add an entry in CHANGES.rst summarizing the change and linking to the issue.
  - [ ] Add .. versionchanged:: entries in any relevant code docs.
• Run pre-commit hooks and fix any issues.
• Run pytest and tox, no tests failed.

[pamelafox]

The typing test is now passing, though I'm confused as to why it was previously failing. Seems like it must be cache related since I can't replicate locally, but I also haven't clearly proved it was cache related. Anyway, passing now.