update changelog

Author: coryodaniel

CHANGELOG.md

@@ -8,6 +8,15 @@ Extending the adopted spec, each change should have a link to its corresponding
 
 ## [Unreleased]
 
+### Added
+
+* Add `enable_basic_auth` set to `true` by default. This will cause a
+  plan change for existing users. Enabling it will require them to set
+  a username and password. [#40]
+* Add `basic_auth_username` set to `""` by default. [#40]
+* Add `basic_auth_password` set to `""` by default. [#40]
+* Add `issue_client_certificate` set to `false` by default. [#40]
+
 ## [v1.0.0] - 2019-03-25
 ### Added
 * Allow creation of service accounts. [#80]
@@ -88,6 +97,7 @@ Extending the adopted spec, each change should have a link to its corresponding
 [#50]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/50
 [#49]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/49
 [#46]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/46
+[#40]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/40
 [#38]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/38
 [#33]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/33
 [#31]: https://github.com/terraform-google-modules/terraform-google-kubernetes-engine/pull/31