doc: release: 4.0: add notes on ZMS

Add notes about the new storage system ZMS

Signed-off-by: Riadh Ghaddab <[email protected]>
(cherry picked from commit f556826)

Author: rghaddab

doc/releases/release-notes-4.0.rst

@@ -401,6 +401,10 @@ Libraries / Subsystems
     from version 2.8.1, the last module update, up to and including
     the released version 2.9.3.
 
+  * :ref:`ZMS<zms_api>`: Introduction of a new storage system that is designed to work with all types of
+    non-volatile storage technologies. It supports classical on-chip NOR flash as well as
+    new technologies like RRAM and MRAM that do not require a separate erase operation at all.
+
 * Task Watchdog
 
 * POSIX API