Test examples and cookbooks

[AstraLuma]

We should see if we can add examples and cookbooks to automated testing, so they don't break.

[ProsperousHeart]

Where are cookbooks located?

[AstraLuma]

https://github.com/ppb/pursuedpybear/tree/canon/docs/howto

[ProsperousHeart]

For clarity, this ask is to write a cookbook in such a way that it can be automated to ensure they are correct (will work) in automated testing - not "please write 'how to write testing files'"

(based on PyCascades 2022 sprint)

[pathunstrom]

@ProsperousHeart with all the research you've done today, please feel free to open a PR adding yourself to the CONTRIBUTORS file. You've been a huge help!