update readme of external secret

Signed-off-by: Carlos Santana <csantana23@gmail.com>

Author: csantanapr

argocd/iac/terraform/examples/eks/external-secrets/README.md

@@ -4,7 +4,7 @@ This example shows how to deploy Amazon EKS with addons configured via ArgoCD
 
 The example demonstrate how to use private git repository for workload apps
 
-Create a secret with name `github-ssh-key` and the content in plain text of git private ssh key
+Create an AWS Secret Manager secret with name `github-ssh-key` and the content in plain text of git private ssh key
 
 Deploy EKS Cluster
 ```shell