Merge pull request #494 from rust-lang/irc-link

feat(community): add irc link

Author: ashleygwilliams

templates/community/index.hbs

@@ -70,6 +70,9 @@
           <li>
             <a href="https://discord.gg/rust-lang" target="_blank" rel="noopener" class="button button-secondary">Discord</a>
           </li>
+          <li>
+            <a href="https://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust" target="_blank" rel="noopener" class="button button-secondary">Mozilla IRC</a>
+          </li>
           <li>
             <a href="/governance" class="button button-secondary">Learn more about teams</a>
           </li>