chore(site): automated update from circleci

Author: kt3k

contact.html

@@ -88,7 +88,7 @@ <h1 id="contact">Contact</h1>
 <hr>
 <h2 id="slack">Slack</h2>
 <ul>
-<li>未登録の方: <a href="https://iojs-jp-slack.herokuapp.com">https://iojs-jp-slack.herokuapp.com</a></li>
+<li>未登録の方: <a href="https://join.slack.com/t/jsconfjp/shared_invite/zt-1j7fqgvbq-Qa334TtwwKWC1eJBrgJ3yQ">jsconf.jp invite link</a></li>
 <li>登録済みの方: <a href="https://iojs-jp.slack.com">https://iojs-jp.slack.com</a></li>
 </ul>
 <h2 id="irc">IRC</h2>