message: docs(do): add more details about the operator
diff: @@ -14,7 +14,7 @@ export function _do<T>(this: Observable<T>, observer: PartialObserver<T>): Obser
  * an Observable that is identical to the source.
  *
  * <span class="informal">Intercepts each emission on the source and runs a
  - * function, but returns an output which is identical to the source.</span>
  + * function, but returns an output which is identical to the source as long as errors don't occur.</span>
  *
  * <img src="./img/do.png" width="100%">
  *
  