Move walkthroughs from user-guide to tutorials. (#8933)

content/en/docs/tutorials/service.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-service
+spec:
+  ports:
+  - port: 8000 # the port that this service should serve on
+    # the container on each pod to connect to, can be a name
+    # (e.g. 'www') or a number (e.g. 80)
+    targetPort: 80
+    protocol: TCP
+  # just like the selector in the deployment,
+  # but this time it identifies the set of pods to load balance
+  # traffic to.
+  selector:
+    app: nginx