V8 Buildbot: Add link to roll status app.

masters/master.client.v8.branches/templates/announce.html

 {% extends "layout.html" %}
 
 {% block header -%}
 {{ super() }}
 <hr/>
 
 <div class="Announcement">
 
 <iframe width="100%" height="44" frameborder="0" scrolling="no" src="https://v8-status.appspot.com/current" ></iframe>
 
 <center style="padding: 0 7px">
   <table width="100%" valign="top" bgcolor="#efefef" style="border-bottom-left-radius: 24px; border-bottom-right-radius: 24px; box-shadow: 2px 2px 6px rgba(0,0,0,0.6);">
     <tr>
       <td style="text-align: center;">
         <b>Sheriff: </b>
         <script src='https://chromium-build.appspot.com/p/chromium/sheriff_v8.js'></script>
         &nbsp;&nbsp;
         <b>Masters: </b>
         <a id="master_v8" href="../client.v8">client.v8</a> |
         <a id="master_v8_branches" href="../client.v8.branches">client.v8.branches</a>
         &nbsp;&nbsp;
-        <b>Controls: </b><a id="tree_status_link" href="https://v8-status.appspot.com">tree status</a>
+        <b>Controls: </b>
+        <a id="tree_status_link" href="https://v8-status.appspot.com">tree status</a> |
+        <a id="roll_status_link" href="https://v8-roll.appspot.com">roll status</a>
       </td>
     </tr>
   </table>
 </center>
 
 </div>
 {% endblock header %}
 
 {% block footer %}
 
 {{ super() }}
 {# <p>Debug info: {{ debuginfo }}</p> #}
 {% endblock %}