VICTORSJG:
Sure, here you go
First screenshot is collections with their actual names, 2nd and 3rd screenshot with sub-collections enabled. So to use sub-collections, just name your collections with a | character where you want the split. The name Series|Harry Potter will result in your Harry Potter sub-collection being
inside the Series collection. I'm guessing it's most useful for series and genres, but I'm sure people will find other uses as well.