renamed timetable in ui

lib/state/app/modules/app_modules.dart

@@ -31,7 +31,7 @@ class AppModule {
     var available = {
       Modules.timetable: AppModule(
         Modules.timetable,
-        name: 'Vertretung',
+        name: 'Stundenplan',
         icon: () => Icon(Icons.calendar_month),
         breakerArea: BreakerArea.timetable,
         create: Timetable.new,