cli: use the new add-host separator

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

content/config/daemon/prometheus.md

@@ -102,7 +102,7 @@ Next, start a Prometheus container using this configuration.
 $ docker run --name my-prometheus \
     --mount type=bind,source=/tmp/prometheus.yml,destination=/etc/prometheus/prometheus.yml \
     -p 9090:9090 \
-    --add-host host.docker.internal:host-gateway \
+    --add-host host.docker.internal=host-gateway \
     prom/prometheus
 ```