Drop Fedora support

Fedora 36 is EOL, also opendev is dropping support for Fedora images
completely since interest in running jobs on that platform is no longer
existing. CentOS 9 Stream has evolved as replacement platform for new
features.

Only drop the Zuul configuration and the tag in stack.sh for now plus
update some docs. Cleanup of the deployment code will be done in a
second step.

Change-Id: Ica483fde27346e3939b5fc0d7e0a6dfeae0e8d1e
diff --git a/doc/source/overview.rst b/doc/source/overview.rst
index a609333..4384081 100644
--- a/doc/source/overview.rst
+++ b/doc/source/overview.rst
@@ -23,13 +23,12 @@
 release.*
 
 -  Ubuntu: current LTS release plus current development release
--  Fedora: current release plus previous release
--  RHEL/CentOS: current major release
+-  RHEL/CentOS/RockyLinux: current major release
 -  Other OS platforms may continue to be included but the maintenance of
    those platforms shall not be assumed simply due to their presence.
    Having a listed point-of-contact for each additional OS will greatly
    increase its chance of being well-maintained.
--  Patches for Ubuntu and/or Fedora will not be held up due to
+-  Patches for Ubuntu and/or RockyLinux will not be held up due to
    side-effects on other OS platforms.
 
 Databases