Sweeping !1252 from master to devel: Allign documentation creation with DIRAC

Unfortunately, we won't be able to get a build feedback before https://github.com/readthedocs/readthedocs.org/issues/9459 is fixed. So this will stay draft for the time being. Once we have the possibility to query RTD for the build status, I'll replace the check_docs job with a job pulling the status from RTD.

UPDATE 22.09.07: since the build passes, we may as well just merge it, so it gets off my todo list. Getting ride of check_docs can be done in a second step.