Update Bug Report diviner document

Summary: Fixes T12922. For now this shuffles open source -> discouse, phacility -> phacility.

Test Plan: Regenerate diviner docs, click on new links.

Reviewers: epriestley, avivey

Reviewed By: avivey

Subscribers: avivey, Korvin

Maniphest Tasks: T12922

Differential Revision: https://secure.phabricator.com/D18229