Review with "Beginner's Mind"

We need this tutorial to be reviewed by a person who is _reasonably_ `new` to both JavaScript and the Elm Architecture so that we can:
+ [ ] _confirm_ that the steps are clear
+ [ ] check code is well explained
+ [ ] ensure nothing is _implied/assumed_ that should be explicit

@edwardcodes please can you read through the instructions in this tutorial, try the examples and open any issues when _anything_ is unclear? (_thanks!_)