Add releasenote to tag the Tempest for 2023.2 release

Updating the doc for the same.

Change-Id: Idfdaabd01cc4e872efca3939e0494b059c14f431
diff --git a/doc/source/supported_version.rst b/doc/source/supported_version.rst
index e86ba39..89f0f90 100644
--- a/doc/source/supported_version.rst
+++ b/doc/source/supported_version.rst
@@ -9,6 +9,7 @@
 
 Tempest master supports the below OpenStack Releases:
 
+* 2023.2
 * 2023.1
 * Zed
 * Yoga