Documentation should highlight the different between field and class deconstruction

[reames@…]

I'm looking at the documentation on ​https://docs.djangoproject.com/en/1.7/topics/migrations/ for the deconstruct() method, where it states:

It takes no arguments, and should return a tuple of 3 things: (path, args, kwargs).

But, it actually should return 4 items as shown in the code:

​https://github.com/django/django/blob/stable/1.7.x/django/db/migrations/state.py#L127

[nliberg]

I too was confused by this at first.
For Fields a 4-tuple including the field name is returned. Documented here: ​https://docs.djangoproject.com/en/1.7/howto/custom-model-fields/#field-deconstruction
For other custom classes a 3-tuple is returned. Documented here: ​https://docs.djangoproject.com/en/1.7/topics/migrations/#custom-deconstruct-method

The latter text should probably mention and link to the former.

[Tim Graham <timograham@…>]

In b829d53b37946d5e3148e2c51ae7ec41f470b756:

Fixed #22497 -- Highlighted difference between field and class deconstruction.

Thanks nliberg for the suggestion.

[Tim Graham <timograham@…>]

In 63ae243a13759f2a87184784fa268d6d003c694a:

[1.7.x] Fixed #22497 -- Highlighted difference between field and class deconstruction.

Thanks nliberg for the suggestion.

Backport of b829d53b37 from master