Update Elchemy installation instructions in the Hackernoon tutorial

[Wolfgang Schuster]

OS: OSX 10.13.6
Elixir: 1.7.2

I was following along with https://hackernoon.com/elmchemy-write-type-safe-elixir-code-with-elms-syntax-part-1-introduction-8968b76d721d When I run mix test I get

== Compilation error in file lib/Hello.elchemy.ex ==
** (CompileError) lib/Hello.elchemy.ex:4: module Elchemy is not loaded and could not be found
    (elixir) expanding macro: Kernel.use/1
    lib/Hello.elchemy.ex:4: Hello (module)

I thought maybe it's because I'm using Elixir 1.7.2, but I really don't know Elixir well enough to diagnose what's going on.

Also, thank you for making such a cool project!

[Krzysztof Wende]

The tutorial is a little bit out of date.
You should be able to use Elchemy installing it as described here:
https://wende.gitbooks.io/elchemy/content/INSTALLATION.html

I leave this issue open to be addressed as a update of the tutorial