docs(eks): minimum size of managed node group can now also be zero (a…

…ws#15103)

Update CDK property doc to reflect new minimum value for EKS managed nodegroup

 * Unit Tests : NA
 * Integration Tests : NA


----

*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/managed-nodegroup.ts

@@ -132,7 +132,7 @@ export interface NodegroupOptions {
  */
  readonly maxSize?: number;
  /**
- * The minimum number of worker nodes that the managed node group can scale in to. This number must be greater than zero.
+ * The minimum number of worker nodes that the managed node group can scale in to. This number must be greater than or equal to zero.
  *
  * @default 1
  */