How to create pod-identity-webhook?

**What happened**:
In my EKS cluster (v1.17), I found pod-identity-webhook but another cluster (v1.15) missing pod-identity-webhook.

**What you expected to happen**:
pod-identity-webhook should be available for v1.15 and v1.16 EKS.

**Environment**:
- AWS Region: ap-southeast-1
- EKS Platform version: "eks.2"
- Kubernetes version: "1.15"
- Webhook Version:

```
➜ kubectl version --short
Client Version: v1.18.4
Server Version: v1.17.9-eks-4c6976
```

The report names no source file, test, or entry point. Start by checking EKS platform and Kubernetes version documentation alongside the repository's installation guidance, then compare pod-identity-webhook behavior for versions 1.15, 1.16, and 1.17. Done means documenting whether the webhook should be present and how it can be created or installed.

Written by the indexing model from the issue text.