Added small comment to explain the classroom_id field in notifications
Added small comment to explain the classroom_id field in notifications

mrpau/kolibri,learningequality/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,mrpau/kolibri,mrpau/kolibri,lyw07/kolibri,mrpau/kolibri,learningequality/kolibri,lyw07/kolibri,indirectlylit/kolibri,learningequality/kolibri,lyw07/kolibri,lyw07/kolibri,learningequality/kolibri