Add a telemetry doc (#2701)
Add a telemetry doc (#2701)

* chore(telemetry): #2700 A checklist for adding Telemetry

rlr/activity-streams,Mardak/activity-stream,rlr/activity-streams,mozilla/activity-streams,JaredKerim-Mozilla/activity-stream,mozilla/activity-streams,Mardak/activity-stream,AdamHillier/activity-stream,AdamHillier/activity-stream,mozilla/activity-stream,mozilla/activity-stream,JaredKerim-Mozilla/activity-stream,sarracini/activity-stream,mozilla/activity-stream,sarracini/activity-stream,AdamHillier/activity-stream,sarracini/activity-stream,rlr/activity-streams,sarracini/activity-stream,JaredKerim-Mozilla/activity-stream,AdamHillier/activity-stream,JaredKerim-Mozilla/activity-stream,Mardak/activity-stream,rlr/activity-streams,mozilla/activity-stream,Mardak/activity-stream