[help wanted] Move documentation to Sphinx+Readthedocs

[PhilipVinc]

Help wanted: anyone who wants to pick this up is welcome.

If you setup the sphinx documentation (markdown please) we can take care of readthedocs integration quite easily.

[wesselb]

Ah, see also my reply here. Would readthedocs be preferable over building the docs with a Github Action and publishing it with Github Pages?

[rtbs-dev]

Documentation has (unofficially?) moved to jupyter book with #57 and #62, so presumably this is closable? :smiley:

[wesselb]

@tbsexton I think so! Though, maybe we should add a small cute snippet to make the landing page (the README) look a little more appealing?