Explain further benefits of hostsMap

morph/lib/customize-monitoring.nix

@@ -3,7 +3,9 @@
 {
   # A set mapping VPN IP addresses as strings to lists of hostnames as
   # strings.  The system's ``/etc/hosts`` will be populated with this
-  # information.
+  # information.  Apart from helping with normal forward resolution, this
+  # *also* gives us reverse resolution from the VPN IPs to hostnames which
+  # allows Grafana to show us hostnames instead of VPN IP addresses.
   hostsMap
 
   # See ``customize-issuer.nix``.