Remove incorrect policy language on Diff reviewers

Summary: Fixes T12952. This never work AFAIK, so resolves this mis-information. See T4411 for follow up.

Test Plan: Click on policy for a diff, no longer see text.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12952

Differential Revision: https://secure.phabricator.com/D18349

src/applications/differential/storage/DifferentialRevision.php

@@ -523,7 +523,6 @@ final class DifferentialRevision extends DifferentialDAO
 
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
-        $description[] = pht("A revision's reviewers can always view it.");
         $description[] = pht(
           'If a revision belongs to a repository, other users must be able '.
           'to view the repository in order to view the revision.');