While using Custome AMI, Controller Role cannot describe images (#2470)

Co-authored-by: Mohamed Iflan Zameer <mi22ban-ext@ads.navvis.com>

Author: iflan7744

website/content/en/v0.16.1/getting-started/migrating-from-cas/scripts/step05-controller-iam.sh

@@ -26,6 +26,7 @@ echo '{
             "Action": [
                 "ssm:GetParameter",
                 "iam:PassRole",
+                "ec2:DescribeImages",
                 "ec2:RunInstances",
                 "ec2:DescribeSubnets",
                 "ec2:DescribeSecurityGroups",