example service monitoring updated with missing config

added service account, role and role binding for the prometheus frontend
example, also updated prometheus to use the correct service account

fixes #1049

manifests/examples/example-app/prometheus-frontend-role.yaml

@@ -0,0 +1,17 @@
+apiVersion: rbac.authorization.k8s.io/v1beta1
+kind: Role
+metadata:
+  name: prometheus-frontend
+  namespace: default
+rules:
+- apiGroups: [""]
+  resources:
+  - nodes
+  - services
+  - endpoints
+  - pods
+  verbs: ["get", "list", "watch"]
+- apiGroups: [""]
+  resources:
+  - configmaps
+  verbs: ["get"]