Merge pull request #27073 from neolit123/1.21-update-containerd-restart-order

container-runtimes: add note about restarting containerd

Author: k8s-ci-robot

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

@@ -147,7 +147,7 @@ Start a Powershell session, set `$Version` to the desired version (ex: `$Version
 {{% /tab %}}
 {{< /tabs >}}
 
-#### systemd {#containerd-systemd}
+#### Using the `systemd` cgroup driver {#containerd-systemd}
 
 To use the `systemd` cgroup driver in `/etc/containerd/config.toml` with `runc`, set
 
@@ -158,6 +158,12 @@ To use the `systemd` cgroup driver in `/etc/containerd/config.toml` with `runc`,
     SystemdCgroup = true
 ```
 
+If you apply this change make sure to restart containerd again:
+
+```shell
+sudo systemctl restart containerd
+```
+
 When using kubeadm, manually configure the
 [cgroup driver for kubelet](/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#configure-cgroup-driver-used-by-kubelet-on-control-plane-node).