Include ModelForm and its Meta options in reference docs

[jernwerber]

ModelForm and the use and structure of a Meta inner class to control what it outputs is covered mostly by way of a topic, ​Creating Forms from Models.

As a developer, it would be helpful to be able to have a consolidated reference for the complete set of possible Meta options (ModelFormOptions) that can be used with a ModelForm's Meta class in a single place, rather than having to infer options from other topics or check the Python source.

[Clifford Gama]

Hi @jernwerber, and thanks for taking the time to create this ticket.

I agree. The reference for ModelForm and the Meta options should be ​here. Although I'm not sure how much we should include there given most of the information is covered in the topic. I think we should start with the signatures, descriptions and the list of Meta options along with what they do.

[jernwerber]

Yep, that makes sense. I've structured by going through the possible/valid attributes for ModelFormOptions and detailing what each would accept/expect and the kinds of errors one might expect to see if something goes wrong.

I wasn't sure where to situate it in the docs since "models.txt" is already taken by the modelform_factory and modelformset_factory docs so for now I just put it under its own thing.

I've done a first pass, here: ​https://github.com/jernwerber/django/blob/docs-modelform-meta/docs/ref/forms/modelform-meta.txt, but before doing some of the formatting (like breaking lines at 80 characters) and making a PR, is there a (non-PR) workflow for this to be reviewed?

Replying to Clifford Gama:

Hi @jernwerber, and thanks for taking the time to create this ticket.

I agree. The reference for ModelForm and the Meta options should be ​here. Although I'm not sure how much we should include there given most of the information is covered in the topic. I think we should start with the signatures, descriptions and the list of Meta options along with what they do.

[jernwerber]

I have created a draft PR for these changes: ​PR

Note: There is still a make warning because I have not added this to any toctrees. Not sure where it should go since the most relevant location is already taken by another ModelForms topic-- I wasn't sure if I could make the call to move things around.