Add example for statefulSetOverride

- related to issue #143

README.md

@@ -6,7 +6,7 @@ The RabbitMQ for Kubernetes Operator is a way of managing [RabbitMQ](https://www
 
 ## Supported Versions
 
-The operator deploys RabbitMQ `3.8.5`, and requires a Kubernetes cluster of `1.16` or above.
+The operator deploys RabbitMQ `3.8.5`, and requires a Kubernetes cluster of `1.16` or `1.17`.
 
 ## Quickstart
 

docs/examples/additionalVolumes/README.md

@@ -0,0 +1,10 @@
+# Additional PersistentVolumeClaim Example
+
+You can leverage StatefulSet override (`spec.Override.StatefulSet`) to modify any property of the statefulSet deployed as part of a RabbitmqCluster instance. `spec.Override.StatefulSet` is in the format of appsv1.StatefulSetSpec. When provided, it will be applied as a patch to the RabbitmqCluster instance StatefulSet definition, using kubernetes [Strategic Merge Patch](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-api-machinery/strategic-merge-patch.md).
+
+The example creates two PersistentVolumeClaim and mounts the additional PersistentVolumeClaim to the `rabbitmq` container.
+
+
+```shell
+kubectl apply -f rabbitmq.yaml
+```

docs/examples/additionalVolumes/rabbitmq.yaml

@@ -0,0 +1,45 @@
+apiVersion: rabbitmq.com/v1beta1
+kind: RabbitmqCluster
+metadata:
+  name: sample
+spec:
+  replicas: 1
+  override:
+    statefulSet:
+      spec:
+        template:
+          spec:
+            containers:
+              - name: rabbitmq
+                volumeMounts:
+                  - name: additional-disk
+                    mountPath: /var/lib/log
+        volumeClaimTemplates:
+          - apiVersion: v1
+            kind: PersistentVolumeClaim
+            metadata:
+              name: persistence
+              namespace: rabbitmq-system
+             labels:
+                "app.kubernetes.io/name": "sample"
+            spec:
+              storageClassName: standard
+              accessModes:
+                - ReadWriteOnce
+              resources:
+                requests:
+                  storage: 3Gi
+          - apiVersion: v1
+            kind: PersistentVolumeClaim
+            metadata:
+              name: persistence-foo
+              namespace: rabbitmq-system
+              labels:
+                "app.kubernetes.io/name": "sample"
+            spec:
+              storageClassName: standard
+              accessModes:
+                - ReadWriteOnce
+              resources:
+                requests:
+                  storage: 1Gi