message: docs(README): Update link to API documentation
  Update the link to API documentation since the current one simply redirects to the new one
diff: @@ -27,7 +27,7 @@ Reactive Extensions Library for JavaScript. This is a rewrite of [Reactive-Exten
  - [Contribution Guidelines](CONTRIBUTING.md)
  - [Maintainer Guidelines](doc/maintainer-guidelines.md)
  - [Creating Operators](doc/operator-creation.md)
  -- [API Documentation (WIP)](http://reactivex.io/rxjs)
  +- [API Documentation (WIP)](https://rxjs-dev.firebaseapp.com/)
  ## Versions In This Repository
  