docs(Observable): fix docs about the share operator

As suggested by ReactiveX#2937 this updates the docs on the share
operator to better reflect it's actual behaviour.

src/operators/share.ts

@@ -13,7 +13,7 @@ function shareSubjectFactory() {
  * Returns a new Observable that multicasts (shares) the original Observable. As long as there is at least one
  * Subscriber this Observable will be subscribed and emitting data. When all subscribers have unsubscribed it will
  * unsubscribe from the source Observable. Because the Observable is multicasting it makes the stream `hot`.
- * This is an alias for .publish().refCount().
+ * This is an alias for .multicast(() => new Subject()).refCount().
  *
  * <img src="./img/share.png" width="100%">
  *