Add 5.1.1 to CHANGELOG

Author: aaron-lane

CHANGELOG.md

@@ -8,6 +8,8 @@ Extending the adopted spec, each change should have a link to its corresponding
 
 ## [Unreleased]
 
+## [v5.1.1] - 2019-10-25
+
 ### Fixed
 
 * Fixed bug with setting up sandboxing on nodes. [#286]
@@ -202,7 +204,8 @@ In either case, upgrading to module version `v1.0.0` will trigger a recreation o
 
 * Initial release of module.
 
-[Unreleased]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v5.1.0...HEAD
+[Unreleased]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v5.1.1...HEAD
+[v5.1.1]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v5.1.0...v5.1.1
 [v5.1.0]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v5.0.0...v5.1.0
 [v5.0.0]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v4.1.0...v5.0.0
 [v4.1.0]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/compare/v4.0.0...v4.1.0