add terraform config for kubectl config file

terraform/eks-cluster.tf

@@ -40,4 +40,10 @@ module "eks" {
             asg_desired_capacity = 1
         }
     ]
+}
+
+resource "local_file" "kube_config_file" {
+    content  = module.eks.kubeconfig
+    filename = "kubeconfig.yaml"
+    file_permission = "400"
 }