Request to update the docs

[Tanner Semerad]

Under the "Basic usage" section of the docs, it says "Add an empty forms.py module at the root of your project."

I'm not sure if that works for most people, but when I viewed a formalchemy_model I got the following error:

AttributeError: 'module' object has no attribute 'FieldSet'

Once I added an import to forms.py everything worked out:

from formalchemy import FieldSet, Grid

I'm running Windows 7 if that matters.