Updated filtering docs to use filterset_fields. (#6415)

Closes #6411.

docs/api-guide/filtering.md

@@ -160,13 +160,13 @@ Or add the filter backend to an individual View or ViewSet.
         ...
         filter_backends = (DjangoFilterBackend,)
 
-If all you need is simple equality-based filtering, you can set a `filter_fields` attribute on the view, or viewset, listing the set of fields you wish to filter against.
+If all you need is simple equality-based filtering, you can set a `filterset_fields` attribute on the view, or viewset, listing the set of fields you wish to filter against.
 
     class ProductList(generics.ListAPIView):
         queryset = Product.objects.all()
         serializer_class = ProductSerializer
         filter_backends = (DjangoFilterBackend,)
-        filter_fields = ('category', 'in_stock')
+        filterset_fields = ('category', 'in_stock')
 
 This will automatically create a `FilterSet` class for the given fields, and will allow you to make requests such as:
 
@@ -188,7 +188,7 @@ When in use, the browsable API will include a `SearchFilter` control:
 The `SearchFilter` class will only be applied if the view has a `search_fields` attribute set.  The `search_fields` attribute should be a list of names of text type fields on the model, such as `CharField` or `TextField`.
 
     from rest_framework import filters
-    
+
     class UserListView(generics.ListAPIView):
         queryset = User.objects.all()
         serializer_class = UserSerializer