Point out Function Execution ARN is needed for Bucket access

README.md

@@ -182,7 +182,7 @@ The deployment relies on an S3 Bucket being available to upload images to. The B
 This is **required** in standard deployments, for integration deployments, a bucket is created and setup for you.
 
 You must allow the `downloader` function `read` and `write` permissions to your bucket, you can find the ARN of the `downloader` function in
-SSM Parameter Store [here](https://us-west-2.console.aws.amazon.com/systems-manager/parameters/) under the name `integration_tests/<IDENTIFIER>/downloader_arn`
+SSM Parameter Store [here](https://us-west-2.console.aws.amazon.com/systems-manager/parameters/) under the name `integration_tests/<IDENTIFIER>/downloader_arn`. Navigate to the function and use its Execution Role ARN within the Buckets permissions to allow access.
 
 
 ## Standard Deployments