Add information how to enable cronjob controller v2

content/en/docs/concepts/workloads/controllers/cron-jobs.md

@@ -32,8 +32,6 @@ The name must be no longer than 52 characters. This is because the CronJob contr
 append 11 characters to the job name provided and there is a constraint that the
 maximum length of a Job name is no more than 63 characters.
 
-
-
 <!-- body -->
 
 ## CronJob
@@ -82,6 +80,14 @@ be down for the same period as the previous example (`08:29:00` to `10:21:00`,)
 The CronJob is only responsible for creating Jobs that match its schedule, and
 the Job in turn is responsible for the management of the Pods it represents.
 
+## New controller
+
+There's an alternative implementation of the CronJob controller, available as an alpha feature since Kubernetes 1.20. To select version 2 of the CronJob controller, pass the following [feature gate](/docs/reference/command-line-tools-reference/feature-gates/) flag to the {{< glossary_tooltip term_id="kube-controller-manager" text="kube-controller-manager" >}}.
+
+```
+--feature-gates="CronJobControllerV2=true"
+```
+
 
 ## {{% heading "whatsnext" %}}
 

content/en/docs/reference/command-line-tools-reference/feature-gates.md

@@ -83,6 +83,7 @@ different Kubernetes components.
 | `CSIVolumeFSGroupPolicy` | `false` | Alpha | 1.19 | |
 | `ConfigurableFSGroupPolicy` | `false` | Alpha | 1.18 | 1.19 |
 | `ConfigurableFSGroupPolicy` | `true` | Beta | 1.20 | |
+| `CronJobControllerV2` | `false` | Alpha | 1.20 | |
 | `CustomCPUCFSQuotaPeriod` | `false` | Alpha | 1.12 | |
 | `CustomResourceDefaulting` | `false` | Alpha| 1.15 | 1.15 |
 | `CustomResourceDefaulting` | `true` | Beta | 1.16 | |
@@ -402,6 +403,7 @@ Each feature gate is designed for enabling/disabling a specific feature:
    Check [Service Account Token Volumes](https://git.k8s.io/community/contributors/design-proposals/storage/svcacct-token-volume-source.md)
    for more details.
 - `ConfigurableFSGroupPolicy`: Allows user to configure volume permission change policy for fsGroups when mounting a volume in a Pod. See [Configure volume permission and ownership change policy for Pods](/docs/tasks/configure-pod-container/security-context/#configure-volume-permission-and-ownership-change-policy-for-pods) for more details.
+- `CronJobControllerV2`: Use an alternative implementation of the {{< glossary_tooltip text="CronJob" term_id="cronjob" >}} controller. Otherwise, version 1 of the same controller is selected. The version 2 controller provides experimental performance improvements.
 - `CPUManager`: Enable container level CPU affinity support, see [CPU Management Policies](/docs/tasks/administer-cluster/cpu-management-policies/).
 - `CRIContainerLogRotation`: Enable container log rotation for cri container runtime.
 - `CSIBlockVolume`: Enable external CSI volume drivers to support block storage. See the [`csi` raw block volume support](/docs/concepts/storage/volumes/#csi-raw-block-volume-support) documentation for more details.