theme: Link to new firmware page

Signed-off-by: Chris Fiege <chris@tinyhost.de>

flamingo/theme/templates/base.html

@@ -117,7 +117,7 @@
                         </div>
                         <div class="col-md-3">
                             <ul class="nav nav-pills nav-stacked">
-                                <li><a href="https://firmware.freifunk-bs.de">Firmware</a></li>
+                                <li><a href="/mitmachen/firmware.html">Firmware</a></li>
                                 <li><a href="http://lists.freifunk.net/mailman/listinfo/braunschweig-freifunk.net">Mailinglist</a></li>
                             </ul>
                         </div>