Release v13 docs (cut over master to production)

This is just a ticket for the regular release task of switching over to v13 docs (master branch to production) that is done when an official release is completed. Ticket to make it easy to track this step.  

When cutover is released (public):
- Merge: https://github.com/inveniosoftware/inveniosoftware.org/pull/227 and publish
