[1.8.x] Fixed #24668 -- Amended ModelAdmin.save_formset() example for #10284.

Thanks Carsten Fuchs.

Backport of e15c55e2bf from master

docs/ref/contrib/admin/index.txt

@@ -1283,6 +1283,8 @@ templates used by the :class:`ModelAdmin` views:
         class ArticleAdmin(admin.ModelAdmin):
             def save_formset(self, request, form, formset, change):
                 instances = formset.save(commit=False)
+                for obj in formset.deleted_objects:
+                    obj.delete()
                 for instance in instances:
                     instance.user = request.user
                     instance.save()