Update Diviner links

Summary:
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

Tags: Diviner

Maniphest Tasks: T15012

Differential Revision: https://we.phorge.it/D25050