Change "Blocking Tasks" property list label to "Blocks"

Summary: Ref T5021. This specific label is a little more clear as "Blocks". See also IRC.

Test Plan: eyeballed it

Reviewers: btrahan, lpriestley, hach-que

Reviewed By: hach-que

Subscribers: epriestley

Maniphest Tasks: T5021

Differential Revision: https://secure.phabricator.com/D9279

src/applications/maniphest/controller/ManiphestTaskDetailController.php

@@ -593,7 +593,7 @@ final class ManiphestTaskDetailController extends ManiphestController {
 
     $edge_types = array(
       PhabricatorEdgeConfig::TYPE_TASK_DEPENDED_ON_BY_TASK
-      => pht('Blocking Tasks'),
+      => pht('Blocks'),
       PhabricatorEdgeConfig::TYPE_TASK_DEPENDS_ON_TASK
       => pht('Blocked By'),
       PhabricatorEdgeConfig::TYPE_TASK_HAS_RELATED_DREV