unguix/prom0-home-rekahsoft-ca/prometheus.sh: Persist metrics

Adjust folder structure of bind mounts so metrics collected by prometheus are persisted
between container removals.

Note: the directory /var/lib/prometheus/data must be owned by `nobody:nogroup` for this to
work

unguix/prom0-home-rekahsoft-ca/prometheus.sh

@@ -4,5 +4,6 @@ docker run -d \
   --name prometheus \
   --restart unless-stopped \
   -p 9090:9090 \
-  -v /var/lib/prometheus:/etc/prometheus \
+  -v /var/lib/prometheus/etc:/etc/prometheus \
+  -v /var/lib/prometheus/data:/prometheus \
 docker.nexus.home.rekahsoft.ca/prom/prometheus:v2.42.0