message: docs: add changelog for 6.0.6
diff: +<a name="6.0.6"></a>
  +## [6.0.6](https://github.com/NativeScript/nativescript-angular/compare/6.0.0...6.0.6) (2018-06-22)
  +
  +> IMPORTANT! You should use this version with @angular/* v6.0.6 and up.
  +
  +### Bug Fixes
  +
  +* clean up properly shared modal page router outlets ([#1360](https://github.com/NativeScript/nativescript-angular/issues/1360)) ([3332ca2](https://github.com/NativeScript/nativescript-angular/commit/3332ca2))
  +* **animations:** inject document object in the animation engine ([#1395](https://github.com/NativeScript/nativescript-angular/issues/1395)) ([379e958](https://github.com/NativeScript/nativescript-angular/commit/379e958)), closes [#1393](https://github.com/NativeScript/nativescript-angular/issues/1393)
  +* **modal:** lower isModalNavigation flag when closing modal ([#1378](https://github.com/NativeScript/nativescript-angular/issues/1378)) ([6ab1cac](https://github.com/NativeScript/nativescript-angular/commit/6ab1cac))
  +
  +
  <a name="6.0.0"></a>
  # [6.0.0](https://github.com/NativeScript/nativescript-angular/compare/5.3.0...6.0.0) (2018-05-30)
  