Doc: Better example for scope builder section of documentation

[kazemihabib]

The code sample for the scope builder section of documentation confuses the new readers.

The problem is the documentation says

The main difference between runBlocking and coroutineScope is that the latter does not block the current thread while waiting for all children to complete.

but the code example below that quote, doesn't show the mentioned difference, because "Coroutine scope is over" is not printed until the nested launch completes so and the new readers might think it's blocking too and confuses them.
Consider this question in stackoverflow
and this one in discuss.kotlin

Changing that example that shows the suspending of the coroutineScope and blocking of runBlocking might help new readers.