Add docs jobs for subunit2sql

During a recent patch series to update the subunit2sql documentation [1]
it was discovered that we were neglecting to build the docs as part of
the jobs run and we weren't publishing them like other projects. This
commit addresses all of these oversights.

[1] https://review.openstack.org/#/q/status:open+project:openstack-infra/subunit2sql+branch:master+topic:docs-update,n,z

Change-Id: Ia382148b11e7dec6f2da7ec47a0573ff40c76109
Merge "Add docs jobs for subunit2sql"