Add "tabindex" to Remarkup reference lists

Summary:
Prevent keyboard focus of these links so we don't disrupt tab order from
comments to "Submit".

Arguably I should make a "function" for this or something but there's nowhere to
really put it that makes any sense right now.

Test Plan: Verified Firefox skips these links in tab order.

Reviewers: fratrik, btrahan, jungejason

Reviewed By: fratrik

CC: aran, fratrik

Maniphest Tasks: T661

Differential Revision: 1180

src/applications/differential/view/addcomment/DifferentialAddCommentView.php

@@ -110,9 +110,10 @@ final class DifferentialAddCommentView extends AphrontView {
             array(
               'href' => PhabricatorEnv::getDoclink(
                 'article/Remarkup_Reference.html'),
+              'tabindex' => '-1',
               'target' => '_blank',
             ),
-            'Remarkup Reference')))
+            'Formatting Reference')))
       ->appendChild(
         id(new AphrontFormSubmitControl())
           ->setValue($is_serious ? 'Submit' : 'Clowncopterize'));

src/applications/maniphest/controller/taskdetail/ManiphestTaskDetailController.php

@@ -412,9 +412,10 @@ class ManiphestTaskDetailController extends ManiphestController {
               'a',
               array(
                 'href' => $remarkup_href,
+                'tabindex' => '-1',
                 'target' => '_blank',
               ),
-              'Remarkup Syntax Reference'))
+              'Formatting Reference'))
           ->setID('transaction-comments'))
       ->appendChild(
         id(new AphrontFormDragAndDropUploadControl())

src/applications/phriction/controller/edit/PhrictionEditController.php

@@ -129,6 +129,8 @@ class PhrictionEditController
       'a',
       array(
         'href' => PhabricatorEnv::getDoclink('article/Remarkup_Reference.html'),
+        'tabindex' => '-1',
+        'target' => '_blank',
       ),
       'Formatting Reference');