Fix readme

Author: psibi

examples/vault-s3-private/README.md

@@ -1,14 +1,10 @@
-# Example showing Vault and private S3 bucket
+# Example showing Vault and IAM Integration
 
 This example creates a private s3 bucket resources. It then uses vault
-to create keys which only has access to the s3 buckets. The example
-code will create an IAM user for each lease and will attach the
-supplied policy with it.
-
-But you can also use STS credentials. You need to change the
-`iam_user` to either `assumed_role` or `federation_token` based on
-your use case. You can find more [details about this
-here](https://www.vaultproject.io/docs/secrets/aws/index.html).
+to create keys which only has access to those s3 buckets. The example
+code will create an IAM role with access to that bucket and will also
+configure vault so that we can dynamically generate credentials for
+accessing that bucket.
 
 ## Requirements