docs(ecs): update ecs Readme example (#23723)

Closes #23635 

----

### All Submissions:

* [ ] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Construct Runtime Dependencies:

* [ ] This PR adds new construct runtime dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-construct-runtime-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [ ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

*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-ecs/README.md

@@ -518,8 +518,8 @@ taskDefinition.addContainer('container', {
   memoryLimitMiB: 1024,
   systemControls: [
     {
-      namespace: 'net',
-      value: 'ipv4.tcp_tw_recycle',
+      namespace: 'net.ipv6.conf.all.default.disable_ipv6',
+      value: '1',
     },
   ],
 });