Update controlplane example in book

Signed-off-by: killianmuldoon <[email protected]>

Author: killianmuldoon

docs/book/src/developer/architecture/controllers/control-plane.md

@@ -229,19 +229,23 @@ The `status` object **may** define several fields:
 
 ## Example usage
 
-``` yaml
-kind: KubeadmControlPlane
-apiVersion: cluster.x-k8s.io/v1alpha3
-metadata:
-  name: kcp-1
-  namespace: default
-spec:
-  infrastructureTemplate:
-    name: kcp-infra-template
-    namespace: default
-  kubeadmConfigSpec:
-    clusterConfiguration:
-  version: v1.16.2
+```yaml
+apiVersion: v1
+items:
+  - apiVersion: controlplane.cluster.x-k8s.io/v1beta1
+    kind: KubeadmControlPlane
+    metadata:
+      name: kcp-1
+      namespace: default
+    spec:
+      machineTemplate:
+        infrastructureRef:
+          apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+          kind: DockerMachineTemplate
+          name: docker-machine-template-1
+          namespace: default
+      replicas: 3
+      version: v1.21.2
 ```
 
 [scale]: https://kubernetes.io/docs/tasks/access-kubernetes-api/custom-resources/custom-resource-definitions/#scale-subresource