doc(decision-tree): update operator/function names (#3912)
doc(decision-tree): update operator/function names (#3912)

#3900
ReactiveX/RxJS,Brocco/RxJS,kwonoj/RxJS,martinsik/rxjs,kwonoj/RxJS,trxcllnt/RxJS,ReactiveX/rxjs,martinsik/rxjs,ReactiveX/rxjs,Brocco/RxJS,kwonoj/RxJS,trxcllnt/RxJS,martinsik/rxjs,ReactiveX/RxJS,benlesh/RxJS,trxcllnt/RxJS,ReactiveX/rxjs,ReactiveX/rxjs,trxcllnt/RxJS,kwonoj/RxJS,ReactiveX/RxJS,benlesh/RxJS,martinsik/rxjs,ReactiveX/RxJS,benlesh/RxJS,Brocco/RxJS,benlesh/RxJS,Brocco/RxJS