message: Update documentation on how to use AWS credentials for testing.
diff: @@ -2,12 +2,15 @@ This folder contains AWS and GCP credentials that are used for testing Tink.
  # AWS
  -The AWS credentials in this folder are used to access only a single test key.
  -Access is also limited to where source IP address is from Google.
  -
  -The credentials are provided in several formats expected by different APIs. For
  +For security reasons, all AWS credentials in this folder are invalid. If you
  +want to run tests that depend on them, please create your own
  +[AWS access keys](https://docs.aws.amazon.com/general/latest/gr/aws-sec-cred-types.html).
  +The credentials are required in several formats expected by different APIs. For
  example, Java expects the credentials as a
  [properties file](https://docs.aws.amazon.com/AmazonS3/latest/dev/AuthUsingAcctOrUserCredentials.html).
  +In order to cover all tests across all languages you will have to replace
  +`aws_credentials_cc.txt`, `credentials_aws.cred`, `credentials_aws.csv` and
  +`credentials_aws.ini`. These can be generated in a similar way to this [script](https://github.com/google/tink/blob/master/kokoro/copy_credentials.sh).
  # GCP
  