[EKS] [request]: Update EKS Windows support doc to reflect VPC-CNI addon configuration

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**Tell us about your request**
What do you want us to build?

The EKS document for enabling Windows support, https://docs.aws.amazon.com/eks/latest/userguide/windows-support.html#enable-windows-support, mentioned that to enable Windows IPAM support, one should

> Create a file named vpc-resource-controller-configmap.yaml with the following contents.
```yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: amazon-vpc-cni
namespace: kube-system
data:
enable-windows-ipam: "true"
```
> Apply the ConfigMap to your cluster.
```bash
kubectl apply -f vpc-resource-controller-configmap.yaml
```

Since the launch of EKS addon configuration, this configmap is now managed by VPC-CNI addon. Manual changes to it, as suggested by the doc, will be overwritten by EKS addon operator, causing unexpected downtime to environments that run Windows workloads.

**Which service(s) is this request for?**
EKS (EKS addon)

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Please update the doc to mention that the `enable-windows-ipam` flag should now be set via VPC-CNI addon configuration
```json
{"enableWindowsIpam": "true"}
```

**Are you currently working around this issue?**
How are you currently solving this problem?
Added above addon configuration to VPC-CNI.

**Additional context**
Anything else we should know?
N/A

**Attachments**
If you think you might have additional information that you'd like to include via an attachment, please do - we'll take a look. (Remember to remove any personally-identifiable information.)

Start with the EKS Windows support documentation at the linked enable-windows-support section and review the current ConfigMap instructions. Update the guidance so the VPC-CNI add-on configuration uses enableWindowsIpam, and remove or revise the manual ConfigMap steps. Done means the page no longer directs users toward settings that the add-on operator can overwrite.

Written by the indexing model from the issue text.