Add breaking change to release notes
=== v4.0.0 (TBA)
* **Breaking Change!** Use `Provider` concept throughout to support lazy evaluation via public API - https://github.com/bmuschko/gradle-docker-plugin/pull/659[Pull Request 659]
+* **Breaking Change!** Consumers of this plugin will have to use Java 8 or higher - https://github.com/bmuschko/gradle-docker-plugin/pull/676[Pull Request 676]
* Introduce method for translating username/password into a PasswordCredentials - https://github.com/bmuschko/gradle-docker-plugin/pull/668[Pull Request 668]
[discrete]
