update README

Author: mr-smithers-excellent

README.md

@@ -26,6 +26,7 @@ If you're experiencing issues, be sure you are using the [latest stable release]
 
 ### v6
 - Multi-platform builds now supported
+- SSH agent forwarding
 
 ### v5
 - AWS ECR [get-login command](https://docs.aws.amazon.com/cli/latest/reference/ecr/get-login.html) became deprecated, migrated to [get-login-password command](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ecr/get-login-password.html)