Add notice text field to events

Add a general text field for communicating extra information that
readers of the schedule should pay special attention to, for example to
highight a change made to the event.

components/TableScheduleEvents.vue

@@ -158,6 +158,7 @@ function newEvent() {
 		!newEventPublic.value,
 		"",
 		false,
+		"",
 		newEventDescription.value,
 		0,
 		new Set(),