reset description when adding an event

sw/lib/addeventkottaspegel.dart

@@ -366,6 +366,7 @@ class _AddEventKottasPegelPageState extends State<AddEventKottasPegel>  {
       configuration.labelConfig.cnt--;
     }
     event.currentEvent.label = configuration.labelConfig.prefix + configuration.labelConfig.cnt.toString();
+    event.currentEvent.description = '';
 
     var date = DateTime.now().toUtc();
     var isoDate = date.toIso8601String();