Enhancement: Sphinx documentation with RTDs

[damian-romero]

Provide documentation through ReadTheDocs.

This tutorial is a good starter. A couple of key points:

1. Docs will be in a docs/ folder relative to the repo parent
2. We will keep source and build separate, so answer yes to that question
3. We will build with python 3.7
4. We will transfer README.md over and have separate sections (separate .rst files)
5. We will use sphinx_rtd_theme HTML theme. You will need to include to include the sphinx_rtd_theme extension

Action item:

• Clean up all docstrings
• Include requirements.txt under docs/ for Sphinx compilation
• Include a GitHub Action script
• Add shields.io badges. See this example