message: docs(aio): add Dart as a language option
diff: ],
  "docVersions": [
  - { "title": "v2", "url": "https://v2.angular.io" }
  + { "title": "v2", "url": "https://v2.angular.io" },
  + { "title": "AngularDart", "url": "https://webdev.dartlang.org/angular" }
  +
  ]
  }
  