docs: buffer and ReplaySubject breaking changes (#6268)
docs: buffer and ReplaySubject breaking changes (#6268)

* docs: add buffer breaking change

* docs: add ReplaySubject breaking change
benlesh/RxJS,martinsik/rxjs,martinsik/rxjs,martinsik/rxjs,ReactiveX/RxJS,ReactiveX/rxjs,ReactiveX/rxjs,ReactiveX/RxJS,martinsik/rxjs,ReactiveX/rxjs,ReactiveX/RxJS,benlesh/RxJS,benlesh/RxJS,ReactiveX/RxJS,ReactiveX/rxjs,benlesh/RxJS