May WTF example

This is a new Rails app with only:

• rails generate controller wtf
• uncommenting the existing test
• requiring the controller in the test
• adding an exit in the related controller

See: https://discuss.rubyonrails.org/t/adding-an-exit-in-a-controller-and-then-running-tests-shows-0-tests-run-but-no-errors/74363 for discussion.