Merge branch 'docs-user-tip-prometheus' into 'master'

Docs: Add a user tip to ease the access to Prometheus

See merge request gitlab-org/gitlab!42591

doc/development/prometheus.md

@@ -47,3 +47,13 @@ using a Prometheus managed application in Kubernetes:
    ```
 
 1. Open `localhost:9090` in your browser to display the Prometheus user interface.
+
+## Script access to Prometheus
+
+You can script the access to Prometheus, extracting the name of the pod automatically like this:
+
+```shell
+POD_INFORMATION=$(kubectl get pods -n gitlab-managed-apps | grep 'prometheus-prometheus-server')
+POD_NAME=$(echo $POD_INFORMATION | awk '{print $1;}')
+kubectl port-forward $POD_NAME 9090:9090 -n gitlab-managed-apps
+```