Add RapidCheck examples to shrinking challenge

[dubzzz]

@jlink, the author of jqwik, a property based testing framework in Java designed a challenge to compare shrinking capabilities of many property based frameworks (whatever the language).

Up to now, 5 frameworks took part in this challenge:

• fast-check - JavaScript
• FsCheck - C#
• Hypothesis - Python
• jqwik - Java
• PropEr - Erlang

I thought that it could be cool to see how RapidCheck deals with such shrinking cases. I personally find this framework amazing, and was sad not to find something as powerful when I moved to JavaScript ecosystem (so I wrote my own for JavaScript). This challenge is also pretty useful as a property based testing framework author as it can help us to find where our frameworks fail or succeed and see how others do in those cases to improve all of them together.

You can find the challenge here: https://github.com/jlink/shrinking-challenge