Clean zh/docs directory for dangling YAML files (#17341)

There are many YAML manifests sneaking into the `zh/docs/` directory.
These files should go to the `zh/examples` directory instead. Having
these "garbage" files (not referenced anywhere) is creating confusion
for the release meister when merging branches. For example, some YAML
files found in the 'master' branch are no longer there in the
release-1.16 branch. It is tedious, if possible at all, to solve all
this kind of conflicts during a rebase.

The PR cleanses the zh/docs directory for all dangling YAML files.

content/zh/examples/application/mysql/mysql-deployment.yaml

@@ -0,0 +1,43 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: mysql
+spec:
+  ports:
+  - port: 3306
+  selector:
+    app: mysql
+  clusterIP: None
+---
+apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
+kind: Deployment
+metadata:
+  name: mysql
+spec:
+  selector:
+    matchLabels:
+      app: mysql
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: mysql
+    spec:
+      containers:
+      - image: mysql:5.6
+        name: mysql
+        env:
+          # Use secret in real usage
+        - name: MYSQL_ROOT_PASSWORD
+          value: password
+        ports:
+        - containerPort: 3306
+          name: mysql
+        volumeMounts:
+        - name: mysql-persistent-storage
+          mountPath: /var/lib/mysql
+      volumes:
+      - name: mysql-persistent-storage
+        persistentVolumeClaim:
+          claimName: mysql-pv-claim

content/zh/examples/application/mysql/mysql-pv.yaml

@@ -0,0 +1,26 @@
+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: mysql-pv-volume
+  labels:
+    type: local
+spec:
+  storageClassName: manual
+  capacity:
+    storage: 20Gi
+  accessModes:
+    - ReadWriteOnce
+  hostPath:
+    path: "/mnt/data"
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: mysql-pv-claim
+spec:
+  storageClassName: manual
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 20Gi