update method
Update a SectionModel
Implementation
@override
Future<SectionModel> update(SectionModel value) {
  return reference.update(value).then((newValue) {
    fullCache[value.documentID] = newValue;
    return newValue;
  });
}Update a SectionModel
@override
Future<SectionModel> update(SectionModel value) {
  return reference.update(value).then((newValue) {
    fullCache[value.documentID] = newValue;
    return newValue;
  });
}