message: docs: add link to the v6 release announcement to our changelog
diff: <a name="6.0.0"></a>
  -# [6.0.0](https://github.com/angular/angular/compare/6.0.0-rc.6...6.0.0) (2018-05-03)
  +# [6.0.0](https://github.com/angular/angular/compare/6.0.0-beta.0...6.0.0) (2018-05-03)
  +
  +### Release Highlights & Update instructions
  +
  +Angular v6 is the first release of Angular that unifies the Framework, Material and CLI.
  +
  +To learn about the release highlights and our new CLI-powered update workflow for your projects please check out the [v6 release announcement](https://blog.angular.io/version-6-0-0-of-angular-now-available-cc56b0efa7a4).
  +
  ### Dependency updates
  -### POSSIBLE BREAKING CHANGES
  +### Possible Breaking Changes
  * **animations:** When animation is triggered within a disabled zone, the associated event (which an instance of AnimationEvent) will no longer report the totalTime as 0 (it will emit the actual time of the animation).
  