Created cmake module to generate module docs

[zachcran]

Status

• Ready to go

Description

This PR is a second attempt at PR #252 without the excessive commits and file history. It completes and is based on PR #206, creating some CMake infrastructure for automatically generating module documentation. This is intended to be used as part of the CI documentation website generation.

As part of the documentation, I included an example of how to use the planned API in a CMake project and how to generate the subsequent documentation website using Sphinx, even if it is not the top-level documentation.

TODOs

• Fix the directory setup from erasing the executable in the process.
• Test for ways to build the documentation when not top-level documentation with Sphinx.
  • (Found a way to do it) Document the process.
• Finish documenting the CMake module using CMinx.
  • Verify that the documentation builds and looks alright.
• Better generated module 'index.rst' files, issue Better generated index.rst #205. I think this should be its own PR separate from the CMake work.