Add a button to download irssi otr from otr.im

Signed-off-by: David Goulet <dgoulet@ev0ke.net>

clients.html

@@ -118,6 +118,7 @@
 			<h2 class="featurette-heading"><a href="https://github.com/cryptodotis/irssi-otr/" target="_blank">Irssi-OTR</a> <span class="text-muted">- an Irssi OTR plugin.</span></h2>
           	<img class="featurette-image align-right img-responsive" src="./assets/img/irssi-otr.png" alt="Irssi-OTR">
           	<p class="lead">Irssi-OTR is a plugin for the Irssi client which offers OTR functionality for those who prefer to work from their terminals.</p>
+		  <p><a class="btn btn-info" href="https://www.otr.im/dist/irssi-otr/" role="button" target="_blank">Download Irssi-OTR&nbsp;»</a></p>
 		  <p><a class="btn btn-info" href="https://github.com/cryptodotis/irssi-otr/" role="button" target="_blank">Fork Irssi-OTR on Github&nbsp;»</a></p>
       </div>