Add link, update date of 1.0.0 in CHANGELOG

Author: aaron-lane

CHANGELOG.md

@@ -6,7 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-## [1.0.0] - 2019-08-05
+## [1.0.0] - 2019-09-06
 
 - Supported version of Terraform is 0.12. [#26]
 
@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Initial release.
 
-[Unreleased]: https://github.com/terraform-google-modules/terraform-google-startup-scripts/compare/v0.1.0...HEAD
+[Unreleased]: https://github.com/terraform-google-modules/terraform-google-startup-scripts/compare/v1.0.0...HEAD
+[1.0.0]: https://github.com/terraform-google-modules/terraform-google-startup-scripts/compare/v0.1.0...v1.0.0
 [0.1.0]: https://github.com/terraform-google-modules/terraform-google-startup-scripts/releases/tag/v0.1.0
-[26]: https://github.com/terraform-google-modules/terraform-google-startup-scripts/pull/26
+[26]: https://github.com/terraform-google-modules/terraform-google-startup-scripts/pull/26