Rails 6 recommends removing `require_dependency`

[StefanWallin]

This gem recommends using require_dependency in the initializer to set up bot reloading in development but those should be removed according to the rails 6 upgrade guide using the Zeitwerk autoloader.

It seems to me that maybe only config.autoload_paths is needed nowadays, so maybe we should update the Readme?

[jgorset]

That sounds about right, @StefanWallin! I wonder if it'll be necessary to change the recommended file structure for Zeitwerk to do it's magic, too, though? I think we'll have to verify this before updating the README accordingly. 🤔 Pull requests welcome!