message: docs(delayWhen): improve docs related to the notification Observable
  Closes
diff: @@ -22,14 +22,28 @@ export function delayWhen<T>(delayDurationSelector: (value: T, index: number) =>
  *
  * ![](delayWhen.png)
  *
  - * `delayWhen` time shifts each emitted value from the source Observable by a
  - * time span determined by another Observable. When the source emits a value,
  - * the `delayDurationSelector` function is called with the source value as
  - * argument, and should return an Observable, called the "duration" Observable.
  - * The source value is emitted on the output Observable only when the duration
  - * Observable emits a value or completes.
  - * The completion of the notifier triggering the emission of the source value
  - * is deprecated behavior and will be removed in future versions.
  + * `delayWhen` operator shifts each emitted value from the source Observable by
  + * a time span determined by another Observable. When the source emits a value,
  + * the `delayDurationSelector` function is called with the value emitted from
  + * the source Observable as the first argument to the `delayDurationSelector`.
  + * The `delayDurationSelector` function should return an Observable, called
  + * the "duration" Observable.
  + *
  + * The source value is emitted on the output Observable only when the "duration"
  + * Observable emits ({@link guide/glossary-and-semantics#next next}s) any value.
  + * Upon that, the "duration" Observable gets unsubscribed.
  + *
  + * Before RxJS V7, the {@link guide/glossary-and-semantics#complete completion}
  + * of the "duration" Observable would have been triggering the emission of the
  + * source value to the output Observable, but with RxJS V7, this is not the case
  + * anymore.
  + *
  + * Only next notifications (from the "duration" Observable) trigger values from
  + * the source Observable to be passed to the output Observable. If the "duration"
  + * Observable only emits the complete notification (without next), the value
  + * emitted by the source Observable will never get to the output Observable - it
  + * will be swallowed. If the "duration" Observable errors, the error will be
  + * propagated to the output Observable.
  *
  * Optionally, `delayWhen` takes a second argument, `subscriptionDelay`, which
  * is an Observable. When `subscriptionDelay` emits its first value or
  