Remove a couple mentions of manipulators (which are no longer relevant) from docs/model-api.txt

    * The widget to use in Django's admin interface, if you care to use it

      (e.g. ``<input type="text">``, ``<select>``).

    * The minimal validation requirements, used in Django's admin and in

      manipulators.

      automatically-generated forms.

Here are all available field types:

``editable``

~~~~~~~~~~~~

If ``False``, the field will not be editable in the admin or via form

processing using the object's ``AddManipulator`` or ``ChangeManipulator``

classes. Default is ``True``.

If ``False``, the field will not be editable in the admin or via forms

automatically generated from the model class. Default is ``True``.

``help_text``

~~~~~~~~~~~~~