Annotations for Calculated Metrics

Feature Request: Add Annotations for Calculated Metrics that are made with Metrics with Annotations.

Use Case: I have a calculated metric of "Room Nights per Order" that showed a historical dip with no annotation available. I then added in Room Nights and Orders on their own to the table, showing the annotations explaining the historical dip. 

I think it would be handy if a calculated metric indicated an annotation when one of the metrics inside the calculated metric has an annotation. Having to add calculated metrics to the annotation list can be cumbersome, and users across our enterprise may have made their own calculated metric and not know about the annotation on one of the metrics. 

Thanks!