docs(README): remove google docs URL (#3657)
docs(README): remove google docs URL (#3657)

The Google Doc's documentation has moved to MIGRATION.md
ReactiveX/rxjs,kwonoj/RxJS,kwonoj/RxJS,ReactiveX/RxJS,martinsik/rxjs,benlesh/RxJS,ReactiveX/RxJS,martinsik/rxjs,trxcllnt/RxJS,ReactiveX/rxjs,Brocco/RxJS,martinsik/rxjs,ReactiveX/RxJS,ReactiveX/RxJS,Brocco/RxJS,kwonoj/RxJS,trxcllnt/RxJS,ReactiveX/rxjs,Brocco/RxJS,benlesh/RxJS,trxcllnt/RxJS,trxcllnt/RxJS,martinsik/rxjs,benlesh/RxJS,Brocco/RxJS,ReactiveX/rxjs,benlesh/RxJS,kwonoj/RxJS