zh_Trans: Fix preview issue (#11311)

* zh_trans: kubeadm-upgrade-1-12.md

* update file

* Update _index.md

* Delete _index.md

* Update kubeadm-upgrade-1-12.md

* zh_trans: docs/reference/setup-tools/kubeadm/generated/kubeadm_config.md

* Update kubeadm_config.md

* zh_trans: fix Preview

* zh_trans: fix Preview

content/zh/examples/application/guestbook/frontend-service.yaml

@@ -0,0 +1,18 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: frontend
+  labels:
+    app: guestbook
+    tier: frontend
+spec:
+  # comment or delete the following line if you want to use a LoadBalancer
+  type: NodePort 
+  # if your cluster supports it, uncomment the following to automatically create
+  # an external load-balanced IP for the frontend service.
+  # type: LoadBalancer
+  ports:
+  - port: 80
+  selector:
+    app: guestbook
+    tier: frontend