More descriptive docs

[nmundar]

Maybe it would be clearer and cleaner if field name parameter is not named 'field' in schema.add_field usage example:

class MyModel(DynamicModel):
    name = models.CharField(max_length=100)  # regular field

schema.add_field(name='field', type='CharField')

I recommend something more descriptive like age to make usage more obvious.

schema.add_field(name='age', type='IntegerField')