Add releasenote to tag the Tempest for 2026.1 release

Also, updating the doc for the same.

Change-Id: If6bbf27e3e0a67f908c6eb67581b14d126f9aceb
Signed-off-by: Ghanshyam Maan <gmaan@ghanshyammann.com>
diff --git a/doc/source/supported_version.rst b/doc/source/supported_version.rst
index f38b6ca..9c03e7f 100644
--- a/doc/source/supported_version.rst
+++ b/doc/source/supported_version.rst
@@ -9,6 +9,7 @@
 
 Tempest master supports the below OpenStack Releases:
 
+* 2025.2
 * 2025.1
 * 2024.2
 * 2024.1