Update retrieving-data-and-resultsets.rst

the documentation write mainly from the point of view of features rather than from the point of view of benefits.

beginners may not even be aware of matching so how can they even find something they are not aware of?

beginners search by the question they have: how do I grab associated data, how do I filter based on associated data? how do i pass options into the inner query.

that is basically what prompted me to write this stackoverflow question, answered brilliantly by ndm.

http://stackoverflow.com/a/28002497/80353