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/index.rst b/doc/source/index.rst
index ccd0fef..a5a11e2 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -37,8 +37,8 @@
 -------------
 
 Start with a clean and minimal install of a Linux system. DevStack
-attempts to support the two latest LTS releases of Ubuntu, the
-latest/current Fedora version, CentOS/RHEL/Rocky Linux 9 and openEuler.
+attempts to support the two latest LTS releases of Ubuntu,
+Rocky Linux 9 and openEuler.
 
 If you do not have a preference, Ubuntu 22.04 (Jammy) is the
 most tested, and will probably go the smoothest.
@@ -113,7 +113,7 @@
 
    $ ./stack.sh
 
-This will take a 15 - 20 minutes, largely depending on the speed of
+This will take 15 - 30 minutes, largely depending on the speed of
 your internet connection. Many git trees and packages will be
 installed during this process.