Description of problem:

The documentation to enable metrics monitoring described here is incorrect and there are some labels needed to add into the `selector` block. Basically, the labels added in the `metadata` must be applied in the `selector` definition.

Apply the definition for a RHDH instance managed by the operator does not work. The metrics are not available in the `Obverser` menu of the `Developer` perspective.

If the Service Monitor is created as this one, the metrics are available:

piVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: rhdh
  labels:
    app.kubernetes.io/instance: <custom_resource_name>
    app.kubernetes.io/name: backstage
spec:
  namespaceSelector:
    matchNames:
      - rhdh-by-operator
  selector:
    matchLabels:
      app.kubernetes.io/instance: <custom_resource_name>
      app.kubernetes.io/name: backstage
  endpoints:
    - port: http-metrics
      path: '/metrics' 

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

1. Create a ServiceMonitor as the doc describes
2. Check metrics in the Observer menu
3. No metrics available

Actual results:

Metrics are not available as developer.

Expected results:

Reproducibility (Always/Intermittent/Only Once): Always

Build Details: Red Hat Developer 1.4.0 (managed by Operator)

Additional info (Such as Logs, Screenshots, etc):