docs(eks): clarify requirements to use subnetSelection (#16632)

partially fixes: #16349 

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*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/fargate-profile.ts

@@ -46,7 +46,7 @@ export interface FargateProfileOptions {
    * By default, all private subnets are selected. You can customize this using
    * `subnetSelection`.
    *
-   * @default - all private subnets used by theEKS cluster
+   * @default - all private subnets used by the EKS cluster
    */
   readonly vpc?: ec2.IVpc;
 
@@ -55,6 +55,8 @@ export interface FargateProfileOptions {
    * on Fargate are not assigned public IP addresses, so only private subnets
    * (with no direct route to an Internet Gateway) are allowed.
    *
+   * You must specify the VPC to customize the subnet selection
+   *
    * @default - all private subnets of the VPC are selected.
    */
   readonly subnetSelection?: ec2.SubnetSelection;