docs(concat): clarify array as input (#4713)
docs(concat): clarify array as input (#4713)

* docs(concat): clarify array as input

Since an array is itself an ObservableInput and so considered as an observable source, specify the use of spread operator to pass an array of observables.

* docs(concat): change array of observables example

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