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]
 
+### Fixed
+
+- **Breaking**: Changed default logging and monitoring providers to new Stackdriver versions. [#384](https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/387)
+
 ## [v6.1.1] - 2019-12-04
 
 ### Fixed