Move openstackdocstheme api-ref job in-tree
Move openstackdocstheme api-ref job in-tree

The repo is master only, we can move the job in-tree.

Change-Id: I35b35fd6c89f81e042b343dd3f1809ac6955660e
Depends-On: https://review.openstack.org/604609

openstack-infra/project-config,openstack-infra/project-config