Doc hygiene: api docs, repo readme, codebase structure

[jianoaix]

Why are these changes needed?

Get docs update to date.

Checks

• [x] I've made sure the lint is passing in this PR.
• [x] I've made sure the tests are passing. Note that there might be a few flaky tests, in that case, please comment that they are not relevant.
• Testing Strategy
  • [ ] Unit tests
  • [ ] Integration tests
  • [ ] This PR is not tested :(