Help link for folder master

gui/index.html

@@ -653,6 +653,7 @@
                     <label>
                       <input type="checkbox" ng-model="currentFolder.readOnly"> <span translate>Folder Master</span>
                     </label>
+                    &nbsp;<a href="http://docs.syncthing.net/users/foldermaster.html" target="_blank"><span class="glyphicon glyphicon-book"></span>&nbsp;<span translate>Help</span></a>
                   </div>
                   <p translate class="help-block">Files are protected from changes made on other devices, but changes made on this device will be sent to the rest of the cluster.</p>
                 </div>