Update header.html

added stack exchange to community menu

_includes/header.html

@@ -55,6 +55,7 @@
             <li><a href="https://forum.getmonero.org">{% t menu.forum %}</a></li>
             <li><a href="https://www.reddit.com/r/monero/">{% t menu.reddit %}</a></li>
             <li><a href="https://bitcointalk.org/index.php?topic=583449.0">{% t menu.bitcointalk %}</a></li>
+            <li><a href="https://monero.stackexchange.com">{% t menu.stackexchange %}</a></li>
             <li class="divider"></li>
             <li class="dropdown-header">{% t menu.irc %}</li>
             <li><a href="irc://chat.freenode.net/#monero">{% t menu.irc-general %}</a></li>
@@ -67,4 +68,4 @@
       </ul>
     </div>
   </div>
-</div>
\ No newline at end of file
+</div>