We stop short of rewriting all playbooks for Prometheus, and instead
add references to the task of adding playbooks for
everything (prometheus-alerts#16) where we found references to
nagios.

howto/upgrades.md

@@ -61,8 +61,8 @@ also `/var/log/dpkg.log`.
 The default configuration file for unattended-upgrades is at
 `/etc/apt/apt.conf.d/50unattended-upgrades`.
 
-Pending upgrades are still noticed by Nagios which warns loudly about them in its
-usual channels.
+Upgrades pending for too long are noticed by monitoring which warns
+loudly about them in its usual channels.
 
 Note that unattended-upgrades is configured to upgrade packages
 regardless of their origin (`Unattended-Upgrade::Origins-Pattern {