update readme about vts metrics

examples/customization/custom-vts-metrics/nginx/README.md

@@ -1,7 +1,11 @@
 # Deploying the Nginx Ingress controller
 
 This example aims to demonstrate the deployment of an nginx ingress controller and
-use a ConfigMap to enable nginx vts module and export metrics for prometheus.
+use a ConfigMap to enable nginx vts module and export metrics for prometheus,to enable 
+vts metric,you can simply run `kubectl apply -f nginx`,a deployment and service will be
+created which already has a `prometheus.io/scrap: 'true'` annotation and if you added
+the recommended Prometheus service-endpoint scraping [configuration](https://raw.githubusercontent.com/prometheus/prometheus/master/documentation/examples/prometheus-kubernetes.yml),
+Prometheus will scrape it automatically and you start using the generated metrics right away.
 
 ## Default Backend
 

examples/customization/custom-vts-metrics/nginx/nginx-ingress-controller-service.yaml

@@ -0,0 +1,18 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-ingress-controller-service
+  namespace: kube-system
+  labels:
+    k8s-app: nginx-ingress-controller-service
+  annotations:
+    prometheus.io/port: '10254'
+    prometheus.io/scrape: 'true'
+spec:
+  ports:
+  - name: http-metrics
+    port: 8080
+    targetPort: 10254
+    protocol: TCP
+  selector:
+    k8s-app: nginx-ingress-controller