Update CHANGELOG.md

Author: morgante

CHANGELOG.md

@@ -8,6 +8,10 @@ Extending the adopted spec, each change should have a link to its corresponding
 
 ## [Unreleased]
 
+### Added
+
+- Added an alternative [update variant](./modules/safer-cluster-update-variant) for the Safer Cluster module. [#378](https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/378)
+
 ## [v6.2.0] - 2019-12-27
 
 ### Fixed