message: docs(Observable): fix typo of document of Observable.ts
diff: @@ -260,7 +260,7 @@ export class Observable<T> implements Subscribable<T> {
  promiseCtor = getPromiseCtor(promiseCtor);
  return new promiseCtor<void>((resolve, reject) => {
  - // Must be declared in a separate statement to avoid a RefernceError when
  + // Must be declared in a separate statement to avoid a ReferenceError when
  // accessing subscription below in the closure due to Temporal Dead Zone.
  let subscription: Subscription;
  subscription = this.subscribe((value) => {
  