add minor explanation about descending order in last section
add minor explanation about descending order in last section

bastilian/Quick-Start-Rails-and-Ruby,vienna-rb/Quick-Start-Rails-and-Ruby,vienna-rb/Quick-Start-Rails-and-Ruby,bastilian/Quick-Start-Rails-and-Ruby,vienna-rb/Quick-Start-Rails-and-Ruby,bastilian/Quick-Start-Rails-and-Ruby,bastilian/Quick-Start-Rails-and-Ruby,vienna-rb/Quick-Start-Rails-and-Ruby