README must explain why not jest-environment-jsdom

[alexanderkjeldaas]

It is impossible to know why I should use this over jest-environment-jsdom by reading the documentation.

[ljharb]

? You shouldn’t, as they’re unrelated. This package is assertion matchers for enzyme wrappers; that one sets up the DOM for your tests.

[blainekasten]

I believe @alexanderkjeldaas is referring to jest-environment-enzyme which is a superset of the jsdom environment.

The documentation for this has been difficult. It's by no means a requirement, just an optional package that can inject globals for React and Enzyme so you don't have to import them in your tests.

If you have any suggestions on how to improve i'm open ears!