Handle custom references in self-hosted Gitlab-CE

Gitlab-CE already handles references for issues (using #), merge requests (!).

I would be interested in handling custom references, but I don’t know whether this is currently possible on a self-hosted Gitlab CE server (version 10.7.3).

Use case

In a commit message, issue or MR description, when a keyword having the form DOC-XXXX is used, it shall be displayed it as [DOC-XXXX](http://doc.myserver.com/references?type=DOC&id=XXXX) DOC-XXXX.