Update changelog 1.6

Author: vikasmb

CHANGELOG/CHANGELOG-1.6.md

@@ -10,6 +10,7 @@ See [code changes](https://github.com/aws/aws-k8s-tester/compare/v1.6.5...v1.6.6
 - Validate ARM AMI type for MNG config [Add support for ARM AMI type in managed node group](https://github.com/aws/aws-k8s-tester/pull/246)
 
 <hr>
+
 ## [v1.6.5](https://github.com/aws/aws-k8s-tester/releases/tag/v1.6.5) (2021-10-15)
 
 See [code changes](https://github.com/aws/aws-k8s-tester/compare/v1.6.4...v1.6.5).