Update instructions to migrate from CentOS Stream 8

Change-Id: I65da7cdfd284a01b2e214c2dc0f27a5f45ae0999

doc/source/support-matrix.rst

@@ -18,15 +18,13 @@ therefore users need to build them by themselves.
 
 .. note::
 
-   CentOS Stream 8 is no longer supported as a host OS. The Yoga release will
-   in future support both CentOS Stream 8 and 9, and provides a route for
-   migration.
+   CentOS Stream 8 is no longer supported as a host OS. The Yoga release
+   supports both CentOS Stream 8 and 9, and provides a route for migration.
 
 .. note::
 
-   Rocky Linux 8 is no longer supported as a host OS. The Yoga release will
-   in future support both Rocky Linux 8 and 9, and provides a route for
-   migration.
+   Rocky Linux 8 is no longer supported as a host OS. The Yoga release supports
+   both Rocky Linux 8 and 9, and provides a route for migration.
 
 Supported container images
 ~~~~~~~~~~~~~~~~~~~~~~~~~~

doc/source/upgrading.rst

@@ -10,9 +10,8 @@ Rocky Linux 9
 =============
 
 The Zed release introduced support for Rocky Linux 9 as a host operating
-system. Rocky Linux 9 support will also be added to Yoga in a future release.
-CentOS Stream 8 users upgrading from Yoga should wait for Rocky Linux 9 support
-to become available before upgrading to Zed.
+system. Rocky Linux 9 support is also available in Yoga. CentOS Stream 8 users
+on Yoga should migrate to Rocky Linux 9 before upgrading to Zed.
 
 Preparation
 ===========