update the yaml example based on review

Author: AlphaWong

content/en/docs/concepts/services-networking/service.md

@@ -546,11 +546,11 @@ spec:
     app: MyApp
   ports:
     - port: 80
-      # By default and for convenience, the targetPort is set to the same value as the port field.
       targetPort: 80
-      # `targetPort` is the port of pod, you would like to expose
-      NodePort: 30007
-      # `NodePort` is the port of node, you would like to expose
+      # By default and for convenience, the `targetPort` is set to the same value as the `port` field.
+      nodePort: 30007
+      # Optional field
+      # By default and for convenience, the Kubernetes control plane will allocates a port from a range (default: 30000-32767)
 ```
 
 ### Type LoadBalancer {#loadbalancer}