Docs: Clean module docs for predict module

[JSchlensok]

Is your feature request related to a problem? Please describe.

The predict module, unlike others, contains classes. When using autosummary and toctree like for other modules, the documentation generated by Sphinx for these classes is not as easy to navigate and not as complete as for methods.

Describe the solution you would like

Auto-generated list of module-level classes and methods in API.rst, ideally excluding methods not exposed in the API (excluded from __all__ in oktoberfest/predict/__init__.py) with links to detailed individual documentation pages.