added menu about

html/index.html.in

@@ -27,6 +27,7 @@
   <li class="toolbutton"><label for="restore">Restore Backup</label><input autocomplete="off" type="file" accept="*.bak" id="restore" /></li>
   <li id="groups" onclick="groups()">Edit Groups</li>
   <li id="android-download" href="safechat.apk"><a href="safechat.apk">Download Android-App</a></li>
+  <li href="https://dev.marc.waeckerlin.org/redmine/projects/safechat/embedded/index.html" target="_blank"><a href="https://dev.marc.waeckerlin.org/redmine/projects/safechat/embedded/index.html" target="_blank">About SafeChat</a></li>
 </ul>
 <script type="text/javascript">
   $(function() { // on load: without cordova, remove andoid-download