Adding example to show labels in POD yaml (#14439)

* Adding example to show labels in POD yaml

This page talk about labels and its usage. Also it talk about syntax for specifying labels. But it does not show how we can have labels in resource manifest. So with this PR i am adding example which shows that how we can have labels in pod manifest.

* Changes to resolve review comments

Changes to resolve review comments

content/en/docs/concepts/overview/working-with-objects/labels.md

@@ -55,6 +55,26 @@ The `kubernetes.io/` and `k8s.io/` prefixes are reserved for Kubernetes core com
 
 Valid label values must be 63 characters or less and must be empty or begin and end with an alphanumeric character (`[a-z0-9A-Z]`) with dashes (`-`), underscores (`_`), dots (`.`), and alphanumerics between.
 
+For example, here’s the configuration file for a Pod that has two labels `environment: production` and `app: nginx` :
+
+```yaml
+
+apiVersion: v1
+kind: Pod
+metadata:
+  name: label-demo
+  labels:
+    environment: production
+    app: nginx
+spec:
+  containers:
+  - name: nginx
+    image: nginx:1.7.9
+    ports:
+    - containerPort: 80
+    
+```
+
 ## Label selectors
 
 Unlike [names and UIDs](/docs/user-guide/identifiers), labels do not provide uniqueness. In general, we expect many objects to carry the same label(s).