Fixed #21516 -- Updated imports paths for some formset functions/classes.

Since refs #21489, FormSet classes and factories are exposed on the
django.forms package.

docs/topics/forms/modelforms.txt

@@ -698,7 +698,7 @@ You can create forms from a given model using the standalone function
 definition. This may be more convenient if you do not have many customizations
 to make::
 
-    >>> from django.forms.models import modelform_factory
+    >>> from django.forms import modelform_factory
     >>> from myapp.models import Book
     >>> BookForm = modelform_factory(Book, fields=("author", "title"))
 
@@ -729,7 +729,7 @@ Like :doc:`regular formsets </topics/forms/formsets>`, Django provides a couple
 of enhanced formset classes that make it easy to work with Django models. Let's
 reuse the ``Author`` model from above::
 
-    >>> from django.forms.models import modelformset_factory
+    >>> from django.forms import modelformset_factory
     >>> from myapp.models import Author
     >>> AuthorFormSet = modelformset_factory(Author, fields=('name', 'title'))
 
@@ -773,7 +773,7 @@ queryset that includes all objects in the model (e.g.,
 Alternatively, you can create a subclass that sets ``self.queryset`` in
 ``__init__``::
 
-    from django.forms.models import BaseModelFormSet
+    from django.forms import BaseModelFormSet
     from myapp.models import Author
 
     class BaseAuthorFormSet(BaseModelFormSet):
@@ -941,7 +941,7 @@ Using a model formset in a view
 Model formsets are very similar to formsets. Let's say we want to present a
 formset to edit ``Author`` model instances::
 
-    from django.forms.models import modelformset_factory
+    from django.forms import modelformset_factory
     from django.shortcuts import render_to_response
     from myapp.models import Author
 
@@ -975,7 +975,7 @@ the unique constraints on your model (either ``unique``, ``unique_together`` or
 on a ``ModelFormSet`` and maintain this validation, you must call the parent
 class's ``clean`` method::
 
-    from django.forms.models import BaseModelFormSet
+    from django.forms import BaseModelFormSet
 
     class MyModelFormSet(BaseModelFormSet):
         def clean(self):
@@ -991,7 +991,7 @@ have already been created for each ``Form``. Modifying a value in
 to modify a value in ``ModelFormSet.clean()`` you must modify
 ``form.instance``::
 
-    from django.forms.models import BaseModelFormSet
+    from django.forms import BaseModelFormSet
 
     class MyModelFormSet(BaseModelFormSet):
         def clean(self):
@@ -1009,7 +1009,7 @@ Using a custom queryset
 As stated earlier, you can override the default queryset used by the model
 formset::
 
-    from django.forms.models import modelformset_factory
+    from django.forms import modelformset_factory
     from django.shortcuts import render_to_response
     from myapp.models import Author
 
@@ -1113,7 +1113,7 @@ you have these two models::
 If you want to create a formset that allows you to edit books belonging to
 a particular author, you could do this::
 
-    >>> from django.forms.models import inlineformset_factory
+    >>> from django.forms import inlineformset_factory
     >>> BookFormSet = inlineformset_factory(Author, Book, fields=('title',))
     >>> author = Author.objects.get(name='Mike Royko')
     >>> formset = BookFormSet(instance=author)
@@ -1137,7 +1137,7 @@ When overriding methods on ``InlineFormSet``, you should subclass
 
 For example, if you want to override ``clean()``::
 
-    from django.forms.models import BaseInlineFormSet
+    from django.forms import BaseInlineFormSet
 
     class CustomInlineFormSet(BaseInlineFormSet):
         def clean(self):
@@ -1152,7 +1152,7 @@ See also :ref:`model-formsets-overriding-clean`.
 Then when you create your inline formset, pass in the optional argument
 ``formset``::
 
-    >>> from django.forms.models import inlineformset_factory
+    >>> from django.forms import inlineformset_factory
     >>> BookFormSet = inlineformset_factory(Author, Book, fields=('title',),
     ...     formset=CustomInlineFormSet)
     >>> author = Author.objects.get(name='Mike Royko')