add irc:// link

lib/views/index.html.ejs

@@ -265,7 +265,7 @@
           <ul>
             <li>Follow us on twitter <a href="https://twitter.com/crafatar" target="_blank">@crafatar</a></li>
             <li>Open an issue <a href="https://github.com/crafatar/crafatar/issues" target="_blank">on GitHub</a></li>
-            <li><a href="https://webchat.esper.net/?channels=crafatar" target="_blank">Join us</a> in #crafatar on irc.esper.net</li>
+            <li><a href="https://webchat.esper.net/?channels=crafatar" target="_blank">Join us</a> in <a href="irc://irc.esper.net/crafatar">#crafatar</a> on irc.esper.net</li>
           </ul>
         </section>
       </section>