chore(eks): deprecate k8s 1.21 and 1.22 (#25575)

```
Hello,

Amazon EKS has deprecated Kubernetes version 1.22 and this version will no longer be supported on June 4, 2023.
 Starting that day, you will no longer be able to create new 1.22 clusters, and all EKS clusters running Kubernetes 
version 1.22 will be updated to the latest available platform version of Kubernetes version 1.23.

You are receiving this message because you currently have 1 or more EKS cluster(s) running with Kubernetes 
version 1.22, listed as follows:

arn:aws:eks:us-east-1:123456789012:cluster/dev-clsuter


We recommend that you update your 1.22 clusters to Kubernetes version 1.23 or higher. You can minimize the frequency
 at which you need to perform version upgrades by updating your cluster up to the latest supported Kubernetes version,
 which is version 1.26.

To learn more on Kubernetes version support, see the Amazon EKS service documentation on Amazon EKS Kubernetes 
versions [1].

For instructions on how to update your cluster(s), see the Amazon EKS service documentation on Updating an Amazon
 EKS cluster Kubernetes version [2].

If you have questions or concerns, please reach out to AWS Support [3].

Sincerely,
Amazon Web Services
```


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: robertd

packages/aws-cdk-lib/aws-eks/README.md

@@ -339,7 +339,7 @@ The following code defines an Amazon EKS cluster with a default Fargate Profile
 
 ```ts
 const cluster = new eks.FargateCluster(this, 'MyCluster', {
-  version: eks.KubernetesVersion.V1_21,
+  version: eks.KubernetesVersion.V1_26,
 });
 ```
 
@@ -416,7 +416,7 @@ You can also configure the cluster to use an auto-scaling group as the default c
 
 ```ts
 const cluster = new eks.Cluster(this, 'HelloEKS', {
-  version: eks.KubernetesVersion.V1_21,
+  version: eks.KubernetesVersion.V1_26,
   defaultCapacityType: eks.DefaultCapacityType.EC2,
 });
 ```
@@ -509,7 +509,7 @@ You can configure the [cluster endpoint access](https://docs.aws.amazon.com/eks/
 
 ```ts
 const cluster = new eks.Cluster(this, 'hello-eks', {
-  version: eks.KubernetesVersion.V1_21,
+  version: eks.KubernetesVersion.V1_26,
   endpointAccess: eks.EndpointAccess.PRIVATE, // No access outside of your VPC.
 });
 ```
@@ -672,8 +672,8 @@ the `@aws-cdk/lambda-layer-awscli` and `@aws-cdk/lambda-layer-kubectl` modules.
 The version of kubectl used must be compatible with the Kubernetes version of the
 cluster. kubectl is supported within one minor version (older or newer) of Kubernetes
 (see [Kubernetes version skew policy](https://kubernetes.io/releases/version-skew-policy/#kubectl)).
-Only version 1.20 of kubectl is available in `aws-cdk-lib`. If you need a different
-version, you will need to use one of the `@aws-cdk/lambda-layer-kubectl-vXY` packages.
+Depending on which version of kubernetes you're targeting, you will need to use one of 
+the `@aws-cdk/lambda-layer-kubectl-vXY` packages.
 
 ```ts
 import { KubectlV26Layer } from '@aws-cdk/lambda-layer-kubectl-v26';

packages/aws-cdk-lib/aws-eks/lib/cluster.ts

@@ -845,11 +845,13 @@ export class KubernetesVersion {
 
   /**
    * Kubernetes version 1.21
+   * @deprecated Use newer version of EKS
    */
   public static readonly V1_21 = KubernetesVersion.of('1.21');
 
   /**
    * Kubernetes version 1.22
+   * @deprecated Use newer version of EKS
    *
    * When creating a `Cluster` with this version, you need to also specify the
    * `kubectlLayer` property with a `KubectlV22Layer` from