Update CHANGELOG.md

Author: morgante

CHANGELOG.md

@@ -169,6 +169,7 @@ Extending the adopted spec, each change should have a link to its corresponding
 [v0.3.0]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v0.2.0...v0.3.0
 [v0.2.0]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v0.1.0...v0.2.0
 
+[#217]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/217
 [#234]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/234
 [#216]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/216
 [#214]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/214