add "squashed" index of CBV reference documentation

[Preston Holmes]

The current CBV reference documentation is organized by mixin, then by view classes documenting attributes and methods where they are defined.

This is a valid approach for documenting the collection of mixins as a "toolkit" for building your own class-based views, but is problematic to use as someone just using the resulting generic class-based views. Understanding just the use of the generic views requires jumping all around the reference documentation by looking at what mixins are used.

Originally I looked into duplicating the reference documentation under two different organizations by updating docstrings and using inspect.getdoc - however the Django documentation is usually more than what is in a docstring, and I didn't want to inject too much doc building machinery. So the compromise was to use a script to traverse the class MRO for each view and generate an alternative index, linking to the current documentation.

this is related to 16807

[Preston Holmes]

​https://github.com/django/django/pull/89

[charlie@…]

I have written something like this at ​http://ccbv.co.uk/ and would really like to get involved with getting something like this into the official docs.

[Tim Graham]

Fixed a couple typos in Preston's original pull request and updated formatting

[Tim Graham <timograham@…>]

In [5faadea439a405ecd80ec06c0d6a769e47ebeec2]:

Fixed #17378 - Added a flattened index for class-based views.

Thanks Preston Holmes for the patch.