update side-by-side example to match the current official recommendations on how to write redux code

[phryneas]

Comparing your library to a style of Redux that isn't actively recommended in the official style guide or taught in the official tutorials seems a little unfair. This updates the Redux part to the officially recommended style of writing & learning Redux nowadays

See The Redux Style Guide, The "Modern Redux" part of the "Fundamentials" tutorial, The full "Essentials" tutorial

Obviously I assume this would also change most of the wording on this page, but I'm already happy if the code itself is up-to-date.