[4.2.x] Fixed typo in docs/ref/models/querysets.txt.

Removed assignment in example for Blog annotation to match shown result.
Backport of addbc90 from main

docs/ref/models/querysets.txt

@@ -2830,15 +2830,15 @@ number of authors that have contributed blog entries:
 .. code-block:: pycon
 
     >>> from django.db.models import Count
-    >>> q = Blog.objects.aggregate(Count("entry"))
+    >>> Blog.objects.aggregate(Count("entry"))
     {'entry__count': 16}
 
 By using a keyword argument to specify the aggregate function, you can
 control the name of the aggregation value that is returned:
 
 .. code-block:: pycon
 
-    >>> q = Blog.objects.aggregate(number_of_entries=Count("entry"))
+    >>> Blog.objects.aggregate(number_of_entries=Count("entry"))
     {'number_of_entries': 16}
 
 For an in-depth discussion of aggregation, see :doc:`the topic guide on