Add LICENSE to GroupLinks controller

app/controllers/projects/group_links_controller.rb

+#-------------------------------------------------------------------
+#
+# The GitLab Enterprise Edition (EE) license
+#
+# Copyright (c) 2013 GitLab.com
+#
+# All Rights Reserved. No part of this software may be reproduced without
+# prior permission of GitLab.com. By using this software you agree to be
+# bound by the GitLab Enterprise Support Subscription Terms.
+#
+#-------------------------------------------------------------------
+
 class Projects::GroupLinksController < Projects::ApplicationController
   layout 'project_settings'