Convert setCaption() to safe HTML

Test Plan: /settings/panel/display/

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2432

Differential Revision: https://secure.phabricator.com/D4824

src/applications/repository/controller/PhabricatorRepositoryArcanistProjectEditController.php

@@ -83,7 +83,8 @@ final class PhabricatorRepositoryArcanistProjectEditController
         id(new AphrontFormTextControl())
           ->setLabel('Indexed Languages')
           ->setName('symbolIndexLanguages')
-          ->setCaption('Separate with commas, for example: <tt>php, py</tt>')
+          ->setCaption(
+            hsprintf('Separate with commas, for example: <tt>php, py</tt>'))
           ->setValue($langs))
       ->appendChild(
         id(new AphrontFormTokenizerControl())