Fix missing comma

Author: amaelftah

resources/lang/en/gitscrum.php

@@ -187,7 +187,7 @@
   'congratulations-the-product-backlog-has-been-updated-with-successfully' => 'Congratulations! The Product Backlog has been successfully updated',
   'favorited-successfully' => 'Favorited',
   'unfavorited-successfully' => 'Unfavorited',
-  'keep-adding' => 'Keep Adding'
+  'keep-adding' => 'Keep Adding',
   'private-sprint' => 'This sprint is private, only owner can access it',
   'save' => 'Save',
   'issue-status-updated' => '@:username updated the issue to: *:status*',