Fixed #15730 - Documented the as_view() method for CBVs.

    **Methods**

    .. classmethod:: as_view(**initkwargs)

        Returns a callable view that takes a request and returns a response::

            response = MyView.as_view(request)

    .. method:: dispatch(request, *args, **kwargs)

        The ``view`` part of the view -- the method that accepts a ``request``

a thread-safe operation).

A class-based view is deployed into a URL pattern using the

:meth:`~View.as_view()` classmethod::

:meth:`~django.views.generic.base.View.as_view()` classmethod::

    urlpatterns = patterns('',

        (r'^view/$', MyView.as_view(size=42)),

    is modified, the actions of one user visiting your view could have an

    effect on subsequent users visiting the same view.

Any argument passed into :meth:`~View.as_view()` will be assigned onto the

instance that is used to service a request. Using the previous example,

this means that every request on ``MyView`` is able to use ``self.size``.

Any argument passed into :meth:`~django.views.generic.base.View.as_view()` will

be assigned onto the instance that is used to service a request. Using the

previous example, this means that every request on ``MyView`` is able to use

``self.size``.

Base vs Generic views

---------------------