Add Description Header/Icon in Pholio

Summary: Add described, simple header and icon with divider.

Test Plan: Tested on an existing mock and created a new mock with and without a description.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8181

src/applications/pholio/controller/PholioMockViewController.php

@@ -219,6 +219,10 @@ final class PholioMockViewController extends PholioController {
 
     $properties->invokeWillRenderEvent();
 
+    $properties->addSectionHeader(
+        pht('Description'),
+        PHUIPropertyListView::ICON_SUMMARY);
+
     $properties->addImageContent(
         $engine->getOutput($mock, PholioMock::MARKUP_FIELD_DESCRIPTION));