Add Sphinx document generation and publish to readthedocs.io

[Tim 'mithro' Ansell]

• https://www.sphinx-doc.org/en/master/
• You probably want to use exhale which allows you to do Doxygen - https://exhale.readthedocs.io/en/latest/
• You might also find the following extensions useful;
  • https://github.com/mithro/sphinxcontrib-session
  • https://github.com/SymbiFlow/sphinxcontrib-verilog-diagrams
  • https://github.com/SymbiFlow/sphinx_materialdesign_theme

Example of how to set this up can be found at https://github.com/SymbiFlow/sphinxcontrib-verilog-diagrams/tree/master/docs and https://github.com/SymbiFlow/sphinxcontrib-verilog-diagrams/blob/master/.readthedocs.yml

[Tim 'mithro' Ansell]

There are various sphinx extensions for YAML and capnp support too.

[Tim 'mithro' Ansell]

The capnproto docs are done with sphinx -> http://capnproto.github.io/
The fomu workshop is done with sphinx -> http://fomu-workshop.fomu.im/
The SymbiFlow docs are done with sphinx -> https://symbiflow.readthedocs.io/en/latest/