[1.7.x] Fixed #22482 -- Recommended using data migrations in contrib.sites docs.

Thanks scibi for the report.

Backport of bbf0a954 from master

docs/ref/contrib/sites.txt

@@ -268,8 +268,8 @@ To enable the sites framework, follow these steps:
 :data:`~django.db.models.signals.post_migrate` signal handler which creates a
 default site named ``example.com`` with the domain ``example.com``. This site
 will also be created after Django creates the test database. To set the
-correct name and domain for your project, you can use an :doc:`initial data
-fixture </howto/initial-data>`.
+correct name and domain for your project, you can use a :ref:`data migration
+<data-migrations>`.
 
 Caching the current ``Site`` object
 ===================================