Add ReactiveX docs link to README

README.md

@@ -121,6 +121,10 @@ Rx.Observable.of('hello world')
   .subscribe(function(x) { console.log(x); });
 ```
 
+## API Documentation
+
+Automatically generated documentation can be found on the ReactiveX website: http://reactivex.io/RxJS
+
 ## Goals
 
 - Provide better performance than preceding versions of RxJS