Enable Prometheus metric

[mug3n451]

Hi, i'm trying to enable the prometheus metric but even if i set the value.yaml no metrics are esposed. Could you tell me if i have to set others parametres?

` prometheus:

Prometheus JMX Exporter: exposes the majority of Kafkas metrics jmx: Interval at which Prometheus scrapes metrics, note: only used by Prometheus Operator interval: 10s

 **Timeout at which Prometheus timeouts scrape run, note: only used by Prometheus Operator**
scrapeTimeout: 10s

** Port jmx-exporter exposes Prometheus format metrics to scrape**
port: 5556

operator: Are you using Prometheus Operator? enabled: true

serviceMonitor:
 **Namespace Prometheus is installed in**
  namespace: monitoring

  # Defaults to whats used if you follow CoreOS [Prometheus Install Instructions](https://github.com/coreos/prometheus-operator/tree/master/helm#tldr)
  # [Prometheus Selector Label](https://github.com/coreos/prometheus-operator/blob/master/helm/prometheus/templates/prometheus.yaml#L65)
  # [Kube Prometheus Selector Label](https://github.com/coreos/prometheus-operator/blob/master/helm/kube-prometheus/values.yaml#L298)
  #selector:
  #  prometheus: kube-prometheus

`

Thanks Cristian