Document the new watcher/member/edit notification mail rules

Summary: Ref T10054. This is mostly for completness so I can reference it when closing all the related tasks.

Test Plan: Read documentation.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10054

Differential Revision: https://secure.phabricator.com/D15066

src/applications/project/application/PhabricatorProjectApplication.php

@@ -135,4 +135,13 @@ final class PhabricatorProjectApplication extends PhabricatorApplication {
     );
   }
 
+  public function getHelpDocumentationArticles(PhabricatorUser $viewer) {
+    return array(
+      array(
+        'name' => pht('Projects User Guide'),
+        'href' => PhabricatorEnv::getDoclink('Projects User Guide'),
+      ),
+    );
+  }
+
 }