kubeadm: add a new page

- Add the new page "Configuring a cgroup driver"
The page includes details on how to configure the cgroup driver
using kubeadm. It also includes a migration guide for users to
move to the "systemd" driver.
- Link to the new page from install-kubeadm.md and container-runtimes.md

content/en/docs/setup/production-environment/container-runtimes.md

@@ -48,7 +48,7 @@ Changing the settings such that your container runtime and kubelet use `systemd`
 stabilized the system. To configure this for Docker, set `native.cgroupdriver=systemd`.
 
 {{< caution >}}
-Changing the cgroup driver of a Node that has joined a cluster is strongly *not* recommended.  
+Changing the cgroup driver of a Node that has joined a cluster is a sensitive operation.
 If the kubelet has created Pods using the semantics of one cgroup driver, changing the container
 runtime to another cgroup driver can cause errors when trying to re-create the Pod sandbox
 for such existing Pods. Restarting the kubelet may not solve such errors.
@@ -57,6 +57,11 @@ If you have automation that makes it feasible, replace the node with another usi
 configuration, or reinstall it using automation.
 {{< /caution >}}
 
+### Migrating to the `systemd` driver in kubeadm managed clusters
+
+Follow this [Migration guide](/tasks/administer-cluster/kubeadm/configure-cgroup-driver)
+if you wish to migrate to the `systemd` cgroup driver in existing kubeadm managed clusters.
+
 ## Container runtimes
 
 {{% thirdparty-content %}}