Dashboard Improvement: See annotations in line graphs

See annotations in the line graphs - We use the annotations to track known anomalies or things we know could affect ups and downs in activity and it would be great if the annotation bubble was hoverable in a dashboard (not always in your face but could hover and see)

@cherise_MixpanelTeam as requested I am submitting all items from @cpellows "dashboard improvements" idea as separate ideas. Please submit product gaps and whenever possible provide a status update. Thank you in advance.