Revert "feat(community): add irc link"

Author: ashleygwilliams

templates/community/index.hbs

@@ -70,9 +70,6 @@
           <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">IRC</a>
-          </li>
           <li>
             <a href="/governance" class="button button-secondary">Learn more about teams</a>
           </li>