Ch13 - compare QuickCheck guide

[milesfrain]

Todos:

• Check if there's any important new content in https://github.com/purescript/purescript-quickcheck/blob/master/GUIDE.md
• Consider linking to that guide in the book.

Another option could be to de-duplicate content between the book and the guide, where the guide contains most of the reference material, and the book contains exercises.

This guide-linking strategy is also used in the "Async Effects" chapter https://book.purescript.org/chapter12.html#additional-aff-resources