Improve mix.exs code sample
Improve mix.exs code sample

lexmag/elixir,beedub/elixir,kimshrier/elixir,antipax/elixir,joshprice/elixir,gfvcastro/elixir,kelvinst/elixir,kimshrier/elixir,pedrosnk/elixir,pedrosnk/elixir,beedub/elixir,lexmag/elixir,ggcampinho/elixir,michalmuskala/elixir,antipax/elixir,gfvcastro/elixir,ggcampinho/elixir,kelvinst/elixir,elixir-lang/elixir