docs: Add the start of a glossary (#5564)
docs: Add the start of a glossary (#5564)

* docs: Add the start of a glossary

* docs(glossary): add streaming, and address comments
ReactiveX/RxJS,martinsik/rxjs,ReactiveX/RxJS,ReactiveX/rxjs,kwonoj/RxJS,kwonoj/RxJS,benlesh/RxJS,benlesh/RxJS,ReactiveX/RxJS,kwonoj/RxJS,ReactiveX/rxjs,benlesh/RxJS,ReactiveX/rxjs,ReactiveX/RxJS,martinsik/rxjs,kwonoj/RxJS,martinsik/rxjs,ReactiveX/rxjs,benlesh/RxJS,martinsik/rxjs