Add samples to Generator and Shrinker documentation

While talking to people about FsCheck I had the following idea to improve the documentation.

The documentation page https://fscheck.github.io/FsCheck/TestData.html which is generated from https://github.com/fscheck/FsCheck/blob/master/docs/content/TestData.fsx currently feels very abstract - I think it would be improved if some of the generators and shrinkers discussed would show some actual output. This would also show people how to write/test generators/shrinkers and get a feel for what they do.

Concretely, I would suggest to add executed code samples (using FSharp.Formatting’s output capturing, like in the other docs) that essentially call Gen.sample and the shrinker function with an example value.

[kurtschelfthout]

Probably better not in this context. Unlikely it should have been part of the API in the first place anyway.

[ploeh]

I think it’d be fine to add an example of Gen.sequence if it’s possible to come up with an easy-to-understand example.

I have to admit, however, that I still don’t understand when I’d ever use Gen.growingElements.

If I understand the intent of this GitHub issue correctly, its purpose is to make the introduction to Generators and Shrinkers more accessible, by showing some examples. The purpose of the TestData.html file isn’t to act as API documentation; there’s a separate page for that.

The reason I bring this up is that if we make the file too big, it’ll have a detrimental effect, because people will give up when they see the sheer size of it.