Update Diviner links
I've deleted the ones branded "phabricator".
Also removed the "target=_blank" stuff, I think it's a bit redundant.
Test Plan: Click all the things
Reviewers: Blessed Committers, Matthew
Reviewed By: Blessed Committers, Matthew
Subscribers: speck, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T15012
Differential Revision: https://we.phorge.it/D25050