docs: fix closing of code block in merge documentation (#3887)
docs: fix closing of code block in merge documentation (#3887)

remove hanging 'javascript' after ``` which breaks formatting of documentation

Closes #3880
ReactiveX/rxjs,benlesh/RxJS,benlesh/RxJS,ReactiveX/RxJS,ReactiveX/RxJS,benlesh/RxJS,ReactiveX/RxJS,trxcllnt/RxJS,kwonoj/RxJS,trxcllnt/RxJS,martinsik/rxjs,ReactiveX/rxjs,benlesh/RxJS,Brocco/RxJS,kwonoj/RxJS,Brocco/RxJS,trxcllnt/RxJS,Brocco/RxJS,ReactiveX/RxJS,Brocco/RxJS,ReactiveX/rxjs,martinsik/rxjs,kwonoj/RxJS,ReactiveX/rxjs,trxcllnt/RxJS,kwonoj/RxJS,martinsik/rxjs,martinsik/rxjs