Update NEWS file regarding disk types

This patch extends the NEWS file describing the essential user-facing
changes in this patch series.

Signed-off-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Michele Tartara <mtarara@google.com>

NEWS

@@ -11,13 +11,15 @@ Version 2.8.0 beta1
 - The :doc:`Remote API <rapi>` daemon now supports a command line flag
   to always require authentication, ``--require-authentication``. It can
   be specified in ``$sysconfdir/default/ganeti``.
-- A new cluster attribute 'enabled_storage_types' is introduced. It will
-  be used to manage the storage types to be used by instances in the cluster.
-  Initially, it will be set to a list that includes lvm, file and sharedfile
-  if those are enabled. Additionally, it will include all storage types that
-  are currently used by instances. The order of storage types will be based
-  on Ganeti's history of supporting them. In the future, the first entry of
-  the list will be used as a default storage type on instance creation.
+- A new cluster attribute 'enabled_disk_templates' is introduced. It will
+  be used to manage the disk templates to be used by instances in the cluster.
+  Initially, it will be set to a list that includes plain, drbd, if they were
+  enabled by specifying a volume group name, and file and sharedfile, if those
+  were enabled at configure time. Additionally, it will include all disk
+  templates that are currently used by instances. The order of disk templates
+  will be based on Ganeti's history of supporting them. In the future, the
+  first entry of the list will be used as a default disk template on instance
+  creation.
 - ``cfgupgrade`` now supports a ``--downgrade`` option to bring the
   configuration back to the previous stable version.