Next-gen documentation infrastructure

[jezdez]

To simplify documentation maintenance and better fit with the rest of our automation work we should:

• Add contributing docs for how to use Sphinx and general documentation workflow #818
• move documentation building with Sphinx into GitHub actions (running in conda/docs repo) #781
• Spike: Bring in sub-projects in main documentation #789
• standardize on one Sphinx theme (e.g. via Revamp Sphinx theme #750)
• Spike: Find a way to ensure old links keep working #790
• Set up a documentation team under the conda governance policy #780
• make use of version for version selection (only for future versions) #779
• Conda docs need automatic copyright year #801
• Improve the landing page of the documentation website conda#11482

[travishathaway]

As we go forward in this epic, we may still consider whether we store built documentation on S3 or GitHub pages (decide by considering SymPy incident)

[jezdez]

Yeah, the idea is to use the same patterns applied in pyscript/pyscript#262 and deploy directly to S3 and not GitHub Pages.