Update mix tasks with note that compilation is necessary for updating… (#1660)
Update mix tasks with note that compilation is necessary for updating… (#1660)

* Update mix tasks with note that compilation is necessary for updating mix help

* Code review changes for note about mix task compilation

* Remove extraneous whitespace

doomspork/elixir_school,doomspork/elixir-school,nscyclone/elixir-school,doomspork/elixir-school,nscyclone/elixir-school,nscyclone/elixir-school,doomspork/elixir_school,doomspork/elixir_school,doomspork/elixir-school,nscyclone/elixir-school