Instructions to set up shared app gateway outdated

**Describe the bug**
The instruction to apply the CRD for `AzureIngressProhibitedTarget` is linked to an older revision on the repository with the `apiVersion` set to `apiextensions.k8s.io/v1beta1`. This no longer works with clusters that are above Kubernetes v1.22 [since it has been deprecated](https://kubernetes.io/docs/reference/using-api/deprecation-guide/#customresourcedefinition-v122). The following error appears:

```
error: resource mapping not found for name: "azureingressprohibitedtargets.appgw.ingress.k8s.io" namespace: "" from "https://raw.githubusercontent.com/Azure/application-gateway-kubernetes-ingress/ae695ef9bd05c8b708cedf6ff545595d0b7022dc/crds/AzureIngressProhibitedTarget.yaml": no matches for kind "CustomResourceDefinition" in version "apiextensions.k8s.io/v1beta1"
```

An updated version of the CRD exists in the repository, so it is simply a matter of updating the instructions to match.

Start with the shared app gateway setup instructions and compare their pinned AzureIngressProhibitedTarget CRD URL with crds/AzureIngressProhibitedTarget.yaml in the repository. Update the instructions to reference the current CRD revision, then verify that the documented apply command uses the non-deprecated API version.

Written by the indexing model from the issue text.