Update used-by section (add coturn)

Author: azat

index.html

@@ -375,6 +375,7 @@ <h3>Programs using libevent</h3>
 <li><a href="http://monkey.org/~provos/dnsscan/">dnsscan</a> &ndash;  a fast scanner for identifying open recursive dns resolvers</li>
 <li><a href="http://code.google.com/p/kargo-event/">Kargo Event</a> &ndash; a PHP extension for libevent.</li>
 <li><a href="http://maximelabelle.bitbucket.org/">Scytale</a> &ndash; a database encryption tool.</li>
+<li><a href="https://github.com/coturn/coturn">Coturn</a> &ndash; Free open source implementation of TURN and STUN Server.</li>
 </ul>
 
 </table>