Updating doc on why we reference an ARN directly.

environments/aws-snowplow/README.md

@@ -53,6 +53,10 @@ have to rotate them manually to have them replaced.
 ### Logs
 You should find logs for any node to be in **/snowplow/logs**.
 
+### SSL Certificate
+This is referenced as an ARN to the cert in AWS. We're not going to put the
+private key in TF, so this will have to remain as an ARN reference.
+
 [[email protected] ~]$ curl http://localhost:8000/health
 OK[[email protected] ~]$