Fixed typo in docs/ref/contrib/gis/install/postgis.txt.

docs/ref/contrib/gis/install/postgis.txt

@@ -67,7 +67,7 @@ The database user must be a superuser in order to run
 ``CREATE EXTENSION postgis;``. The command is run during the :djadmin:`migrate`
 process. An alternative is to use a migration operation in your project::
 
-    from django.contrib.postgresql.operations import CreateExtension
+    from django.contrib.postgres.operations import CreateExtension
     from django.db import migrations
 
     class Migration(migrations.Migration):