Chalk must be added to the model after Ecto

[ivanhercaz]

It must be interesting to specify in the README's "Setup" section that Chalk must be added after the lines use Ecto.Schema and import Ecto.Changeset. If it is added before of any of these lines, one of them or both, it returns an error:

error: undefined function cast/3 (expected App.Accounts.User to define such a function or for it to be imported, but none are available)