message: docs(interval): more practical example
diff: @@ -21,10 +21,22 @@ import { Subscriber } from '../Subscriber';
  * {@link SchedulerLike} to it.
  *
  * ## Example
  - * Emits ascending numbers, one every second (1000ms)
  + * Emits ascending numbers, one every second (1000ms) up to the number 3
  * ```javascript
  + * import { interval } from 'rxjs';
  + * import { take } from 'rxjs/operators';
  + *
  * const numbers = interval(1000);
  - * numbers.subscribe(x => console.log(x));
  + *
  + * const takeFourNumbers = numbers.pipe(take(4));
  + *
  + * takeFourNumbers.subscribe(x => console.log('Next: ', x));
  + *
  + * // Logs:
  + * // Next: 0
  + * // Next: 1
  + * // Next: 2
  + * // Next: 3
  * ```
  *
  * @see {@link timer}
  