Cookbooks should have branched sub-cookbooks in response to questions / variants on the top-level cookbooks

For example, in data-mocking: https://github.com/ember-learn/cookbook/issues/13

you may want MSW in dev, not in dev, in tests, or whatever.

explaining how to:
- remove in non-tests environments
- add mock data per test
- etc

would be a good example of sub-cookbooks