As you can see here David Pilato points out the documentation is not up to date.
Sorry for make you upset, it wasn't my intention. I hope we can still be friends 
This post going to help many people in the near future cos as you said there are not many ec2-discovery expert here, and if someone going to look for a solution with a similar problem whit any keywords which are in the title, they need to see a solution or any ideas regarding this problem.