Add TCP socket health check example (#3977)

* Add TCP socket health check example

* Add test case for pod-with-tcp-socket-healthcheck

docs/user-guide/walkthrough/pod-with-tcp-socket-healthcheck.yaml

@@ -0,0 +1,19 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: pod-with-tcp-socket-healthcheck
+spec:
+  containers:
+  - name: redis
+    image: redis
+    # defines the health checking
+    livenessProbe:
+      # a TCP socket probe
+      tcpSocket:
+        port: 6379
+      # length of time to wait for a pod to initialize
+      # after pod startup, before applying health checking
+      initialDelaySeconds: 30
+      timeoutSeconds: 1
+    ports:
+    - containerPort: 6379