added hint that this works with Amazon Linux only

Author: michaelwittig

README.md

@@ -1,6 +1,6 @@
 # Manage AWS EC2 SSH access with IAM
 
-Use your IAM user's public SSH key to get access via SSH to an EC2 instance.
+Use your IAM user's public SSH key to get access via SSH to an EC2 instance with **Amazon Linux**.
 
 ## How does it work