tox: Add a sphinx environment to check sane doc build
Now that all sphinx warnings have been fixed by @vlorentz, it would be great to avoid introducing new ones as much as possible.
This diff showcases how a sphinx
environment can be added to tox
to build and check the documentation proper to a swh package.
As some external references could not be resolved in a single package scope, related sphinx warnings are suppressed for the build to succeed but other ones are not.
This would allow to catch any rst errors prior landing a diff.
Ideally a new parallel step in our Jenkins pipelines to build and check the doc should be added. We already have a CI docker image containing all the required tools to build the doc so this should not be too complicated to integrate.
Depends on D5571
Migrated from D5550 (view on Phabricator)