docs: resurface googleapis.dev and prediction docs

[dandhlee]

I've mistakenly broken some of the docs for types links on googleapis.dev. Fixing the docs structure so the docs are showing again. If you run nox -s docs and take a look around the docs, they'll be back up.

I've verified that prediction pages are back up on c.g.c.

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #1722 🦕