Docs: Fix attributes example

This fix was supplied in #1686.

Fixes #1686.

docs/source/topics/modelling_your_catalogue.rst

@@ -47,7 +47,8 @@ You can go as far as associating arbitrary models with it. Use the ``entity``
 type::
 
     > klass = ProductClass.objects.create(name='foo', slug='bar')
-    > ProductAttribute.objects.create(product_class=klass, name='admin user', code='admin_user')
+    > ProductAttribute.objects.create(
+          product_class=klass, name='admin user', code='admin_user', type='entity')
     <ProductAttribute: admin user>
     > p = Product(product_class=klass)
 
@@ -76,4 +77,4 @@ Going further
 
 Oscar's modelling options don't stop there. If the existing framework does not
 suit your need, you can always :doc:`customise </howto/how_to_customise_models>`
-any involved models. E.g. the ``Product`` model is often customised!
+any involved models. E.g. the ``Product`` model is often customised!