Add wordpress example for demonstrating variable reference

examples/wordpress/wordpress/deployment.yaml

@@ -0,0 +1,29 @@
+apiVersion: apps/v1beta2 # for versions before 1.9.0 use apps/v1beta2
+kind: Deployment
+metadata:
+  name: wordpress
+  labels:
+    app: wordpress
+spec:
+  selector:
+    matchLabels:
+      app: wordpress
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: wordpress
+    spec:
+      containers:
+      - image: wordpress:4.8-apache
+        name: wordpress
+        ports:
+        - containerPort: 80
+          name: wordpress
+        volumeMounts:
+        - name: wordpress-persistent-storage
+          mountPath: /var/www/html
+      volumes:
+      - name: wordpress-persistent-storage
+        emptyDir: {}