docs(observable.md): Fixed broken link in Observable guide documentation. (#4882)
docs(observable.md): Fixed broken link in Observable guide documentation. (#4882)


kwonoj/RxJS,ReactiveX/rxjs,martinsik/rxjs,ReactiveX/RxJS,ReactiveX/RxJS,benlesh/RxJS,benlesh/RxJS,benlesh/RxJS,ReactiveX/RxJS,ReactiveX/rxjs,trxcllnt/RxJS,kwonoj/RxJS,ReactiveX/rxjs,trxcllnt/RxJS,kwonoj/RxJS,martinsik/rxjs,martinsik/rxjs,trxcllnt/RxJS,martinsik/rxjs,trxcllnt/RxJS,benlesh/RxJS,ReactiveX/RxJS,kwonoj/RxJS,ReactiveX/rxjs