review all nagios metrics (#40755)

howto/prometheus.md

@@ -394,18 +394,6 @@ Basically, Prometheus is similar to Munin in many ways:
    without sending duplicate alerts - `munin-limits` can only run on a
    single server
 
-## Migrating from Icinga / Nagios
-
-Key metric equivalence:
-
- * uptime: `time()-node_boot_time_seconds` ([source](https://github.com/m-lab/prometheus-support/issues/91#issuecomment-687785774)) also: count
-   reboots per day: `changes(process_start_time_seconds[1d])`, see
-   also [alerting on crash loops](https://www.robustperception.io/alerting-on-crash-loops-with-prometheus/)
- * availability: `avg_over_time(up{job="node"}[7d])` ([source](https://gitlab.torproject.org/tpo/tpa/team/-/issues/29864#note_2540787))
-
-More ideas in [this issue](https://gitlab.torproject.org/tpo/tpa/team/-/issues/29864), followup on the migration in [this
-issue](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40755). See also [TPA-RFC-33: Monitoring](policy/tpa-rfc-33-monitoring).
-
 ## Push metrics to the Pushgateway
 
 The [Pushgateway][] is setup on the secondary Prometheus server