Add example for changing admission controllers

Closes: #4445

docs/admin/admission-controllers.md

@@ -56,6 +56,19 @@ support all the features you expect.
 
 The Kubernetes API server supports a flag, `admission-control` that takes a comma-delimited,
 ordered list of admission control choices to invoke prior to modifying objects in the cluster.
+For example, the following command line turns on the `NamespaceLifecycle` and the `LimitRanger`
+admission controller:
+
+```shell
+kube-apiserver --admission-control=NamespaceLifecyle,LimitRanger ...
+```
+
+**Note**: Depending on the way your Kubernetes cluster is deployed and how the
+API server is started, you may need to apply the settings in different ways.
+For example, you may have to modify the systemd unit file if the API server is
+deployed as a systemd service, you may modify the manifest file for the API
+server if Kubernetes is deployed in a self-hosted way.
+{: .note}
 
 ## What does each admission controller do?