[1.8.x] Replaced "inbuilt" with more common "built-in".

Backport of a8f05f40 from master

docs/ref/models/querysets.txt

@@ -2213,7 +2213,7 @@ specified as keyword arguments to the ``QuerySet`` methods :meth:`filter()`,
 For an introduction, see :ref:`models and database queries documentation
 <field-lookups-intro>`.
 
-Django's inbuilt lookups are listed below. It is also possible to write
+Django's built-in lookups are listed below. It is also possible to write
 :doc:`custom lookups </howto/custom-lookups>` for model fields.
 
 As a convenience when no lookup type is provided (like in

docs/releases/1.7.txt

@@ -280,7 +280,7 @@ Custom lookups
 ~~~~~~~~~~~~~~
 
 It is now possible to write custom lookups and transforms for the ORM.
-Custom lookups work just like Django's inbuilt lookups (e.g. ``lte``,
+Custom lookups work just like Django's built-in lookups (e.g. ``lte``,
 ``icontains``) while transforms are a new concept.
 
 The :class:`django.db.models.Lookup` class provides a way to add lookup