Document metrics server

[Jonty]

Not sure where we're publishing public metrics yet for this year? Grafana?

[edwinbalani]

stats.emf.camp, once it's back up on site, will present a Grafana backed by a Prometheus database. Right now we (NOC monitoring squad) are planning on the following:

• Bar stats
• Anything we want from MQTT (ref. Document MQTT #15)
• NOC stats (might not all be public?)

If it can be polled by Prometheus or published to MQTT, it should be easy for us to pull it in and pipe it through to Grafana!