Update EKS deployment documentation

[harshal-shah]

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---

Summary

The EKS deployment page seems to be copied from GKE and hence contains some incorrect information.
For example:
Service of type LoadBalancer on EKS will create an AWS ELB which does not have a external IP but instead has a hostname
so the status field in the service shall be like below:

    "status": {
        "loadBalancer": {
            "ingress": [
                {
                    "hostname": "testtesttesttesttest.eu-west-1.elb.amazonaws.com"
                }
            ]
        }
    }

The proxy IP export command should be as follows:

export PROXY_IP=$(kubectl get -o jsonpath="{.status.loadBalancer.ingress[0].hostname}" service -n kong kong-proxy)

[hbagdi]

PR welcome to fix it!