chore(eks): deprecate older versions of EKS (#18842)

EKS version support: https://docs.aws.amazon.com/eks/latest/userguide/kubernetes-versions.html

Kubernetes versions: https://endoflife.date/kubernetes


----

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

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

@@ -772,21 +772,25 @@ export interface ClusterProps extends ClusterOptions {
 export class KubernetesVersion {
   /**
    * Kubernetes version 1.14
+   * @deprecated Use newer version of EKS
    */
   public static readonly V1_14 = KubernetesVersion.of('1.14');
 
   /**
    * Kubernetes version 1.15
+   * @deprecated Use newer version of EKS
    */
   public static readonly V1_15 = KubernetesVersion.of('1.15');
 
   /**
    * Kubernetes version 1.16
+   * @deprecated Use newer version of EKS
    */
   public static readonly V1_16 = KubernetesVersion.of('1.16');
 
   /**
    * Kubernetes version 1.17
+   * @deprecated Use newer version of EKS
    */
   public static readonly V1_17 = KubernetesVersion.of('1.17');