doc: add new doc website

[ryantm]

• use mmdoc
• add github pages action to auto publish
• do not edit README for now, will follow up with a commit directs people to the doc site

[n8henrie]

Not familiar with mmdoc, will check it out

[n8henrie]

Not familiar with mmdoc, will check it out

https://github.com/ryantm/mmdoc

Ah, cool -- it's your tool, and what you used for e.g. https://ryantm.github.io/nixpkgs/languages-frameworks/python/ (pages that I've been really grateful for!)