Make membership lock/unlock feed stories read more naturally

Summary: Ref T12732. This is pre-existing.

Test Plan: {F4967438}

Reviewers: chad, amckinley

Reviewed By: chad

Maniphest Tasks: T12732

Differential Revision: https://secure.phabricator.com/D17969

src/applications/project/storage/PhabricatorProjectTransaction.php

@@ -209,12 +209,12 @@ final class PhabricatorProjectTransaction
       case self::TYPE_LOCKED:
         if ($new) {
           return pht(
-            '%s locked %s membership.',
+            '%s locked membership for %s.',
             $author_handle,
             $object_handle);
         } else {
           return pht(
-            '%s unlocked %s membership.',
+            '%s unlocked membership for %s.',
             $author_handle,
             $object_handle);
         }