add publish docs job to CI

[arezaii]

This adds a new job to our CI process that will conditionally trigger on pushes to main. The new job depends on the make_doc job finishing, and then it retrieves the documentation artifact from that job. For now, it just finishes by listing the contents of the directory and the index.html, but the idea is that this job can sync the docs to the web.

Next steps required to sync docs to web:

• store webhost key as github secret
• update ci script to rsync docs to webhost