doc: Drop old Django information
The dropped information is about Ussuri release which dropped
Django 1.11 support. The information is no longer needed
as we are in Wallaby release.
Note that the referred bug is about a typo in the dropped note.
Closes-Bug:
@@ -9,9 +9,6 @@ The Ussuri release of horizon has the following dependencies.
* Django 2.2
* Django support policy is documented at :ref:`django_support`.
- * Ussuri release uses Django 2.2 (the latest LTS) as the primary Django
- version. The prevouos LTS of Django 1.11 will be dropped during
- Ussuri cycle. Django 2.0 support will be dropped as well.
* An accessible `keystone <https://docs.openstack.org/keystone/latest/>`_ endpoint
