Update README.md

Author: dmattia

README.md

@@ -4,4 +4,8 @@ A terraform module for creating Lambda@Edge functions.
 
 This module supports any type of Lambda Function supported by Edge, including NodeJs and Python functions.
 
-You just point it at a set of local file globs and it handles bundling your code and deploying it.
+You just point it at a set of local file globs and it handles bundling your code and deploying it.
+
+## Requirements
+
+You must use a versioned S3 bucket for your deployment artifacts