Docs: 1.4.0 release note

Change-Id: If725909a3a87a73563efddf1b95227634e2109c0
Co-authored-by: Summer Qin <summer.qin@arm.com>
Signed-off-by: Ken Liu <Ken.Liu@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 060beba..162db66 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,7 +7,7 @@
 
 cmake_minimum_required(VERSION 3.15)
 
-set(TFM_VERSION 1.3.0)
+set(TFM_VERSION 1.4.0)
 
 ############################ CONFIGURATION #####################################