add missing comma (#435)

Author: dirk-thomas

ros_buildfarm/templates/status/release_status_page.html.em

@@ -59,7 +59,7 @@
       <a href="?q=RED">RED</a>,
       <a href="?q=ORANGE">ORANGE</a>,
       <a href="?q=YELLOW">YELLOW</a>,
-      <a href="?q=GRAY">GRAY</a>
+      <a href="?q=GRAY">GRAY</a>,
       <a href="?q=UNMAINTAINED" title="Filter packages with unmaintained status">UNMAINTAINED</a>
     </p>
     <form action="?">