Fixed example of configmap containing prometheus rules and alerts config

prometheus-rules-configmap.yaml

apiVersion: v1
data:
  prometheus.rules: |
    # TODO add rules
  prometheus.alerts: |
    # host rules
    ALERT high_node_load
      IF node_load1 > 20
      FOR 10s
      LABELS { severity = "critical" }
      ANNOTATIONS {
          # summary defines the status if the condition is met
          summary = "Node usage exceeded threshold",
          # description reports the situtation of event
          description = "Instance {{ $labels.instance }}, Job {{ $labels.job }}, Node load {{ $value }}",
      }
kind: ConfigMap
metadata:
  creationTimestamp: null
  name: prometheus-rules