[Docs] Add docstring to documentation generation with Sphinx Napoleon

[chenyenru]

Description: Add documentation generation from docstring.

Question:
Per sphinx-apidoc's documentation, building the documentation requires all required dependencies as if developing the code. Else, complete documentation will not be generated. Is there a way to test the edits in .readthedocs.yaml to see if all required dependencies are installed and that documentations are successfully generated?

[StoneT2000]

These changes were copied over in a larger docs overhaul in #516