Fixed typo in docs/ref/models/indexes.txt.
@@ -115,7 +115,7 @@ indexes records with more than 400 pages.
.. admonition:: Restrictions on PostgreSQL
- PostgreSQL requires functions referenced in the condition to be be marked as
+ PostgreSQL requires functions referenced in the condition to be marked as
IMMUTABLE. Django doesn't validate this but PostgreSQL will error. This
means that functions such as :ref:`date-functions` and
:class:`~django.db.models.functions.Concat` aren't accepted. If you store
