Fixed typo in aggregation docs link.

docs/topics/db/aggregation.txt

@@ -193,7 +193,7 @@ modified using any other ``QuerySet`` operation, including ``filter()``,
     yield the wrong results, as `multiple tables are cross joined`_,
     resulting in duplicate row aggregations.
 
-.. _multiple tables are the cross joined: https://code.djangoproject.com/ticket/10060
+.. _multiple tables are cross joined: https://code.djangoproject.com/ticket/10060
 
 Joins and aggregates
 ====================