Set up sphinx + doxygen documentation generation

[mithro]

We should publish verible documentation on ReadTheDocs using Sphinx.

For HDL related projects like google/skywater-pdk, prjxray and verilog-to-routing we have standardized on using Sphinx (and on C++ projects Doxygen stuff being pulled into Sphinx).

There is also sphinxcontrib-verilog-diagrams which renders nice diagrams from Verilog and sphinx_symbiflow_theme which renders the documentation in material design.

[mithro]

Related issues;

• https://github.com/alainmarcel/Surelog/issues/305
• https://github.com/alainmarcel/UHDM/issues/40

Demo documents;

• 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/

[mithro]

FYI -- @rw1nkler

[mithro]

@rw1nkler set this up for the VerilogToRouting repository and it can be seen at https://docs.verilogtorouting.org/en/latest/api/vpr/contexts/

[rw1nkler]

Some useful resources for adding Sphinx+Breathe integration (C/C++ support):

• Breathe Quickstart
• Initial Sphinx+Breathe Support (VTR)
• API Documentation for C/C++ Projects (VTR)