docs update to reflect includes.yml
People wanting to extend this CI should probably start from includes.yml not builddebs.yml, so update the README to reflect that.
How to register an account on GitLab. To prevent spam, new accounts are locked until approved by an admin or the approver bot. You can also file an unlock request to expedite access.
Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
People wanting to extend this CI should probably start from includes.yml not builddebs.yml, so update the README to reflect that.