docs: update Kubernetes deployments

docs/how-tos/deploy-on-kubernetes.md

@@ -230,7 +230,6 @@ spec:
 
 This image also supports Kubernetes security context, you can run it in Rootless environment.
 It has been tested on Openshift, it works well.
-Deployment on Openshift is supported, you need to remove `securityContext` section on your yaml file.
 
 ```yaml
 apiVersion: batch/v1
@@ -289,3 +288,55 @@ spec:
               #  value: "xxx"
           restartPolicy: OnFailure
 ```
+
+## Migrate database
+
+```yaml
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: migrate-db
+spec:
+  ttlSecondsAfterFinished: 100
+  template:
+    spec:
+      containers:
+        - name: pg-bkup
+          # In production, it is advised to lock your image tag to a proper
+          # release version instead of using `latest`.
+          # Check https://github.com/jkaninda/pg-bkup/releases
+          # for a list of available releases.
+          image: jkaninda/pg-bkup
+          command:
+            - /bin/sh
+            - -c
+            - migrate
+          resources:
+            limits:
+              memory: "128Mi"
+              cpu: "500m"
+          env:
+            ## Source Database
+            - name: DB_HOST
+              value: "postgres"
+            - name: DB_PORT
+              value: "5432"
+            - name: DB_NAME
+              value: "dbname"
+            - name: DB_USERNAME
+              value: "username"
+            - name: DB_PASSWORD
+              value: "password"
+            ## Target Database
+            - name: TARGET_DB_HOST
+              value: "target-postgres"
+            - name: TARGET_DB_PORT
+              value: "5432"
+            - name: TARGET_DB_NAME
+              value: "dbname"
+            - name: TARGET_DB_USERNAME
+              value: "username"
+            - name: TARGET_DB_PASSWORD
+              value: "password"
+      restartPolicy: Never
+```