doc: releases: 4.1: Documet PM removed API

Adding information about z_pm_save_idle_exit removal.

Signed-off-by: Flavio Ceolin <[email protected]>

Author: ceolin

doc/releases/release-notes-4.1.rst

@@ -82,6 +82,8 @@ Removed APIs and options
 * The :kconfig:option:`CONFIG_PM_DEVICE_RUNTIME_EXCLUSIVE` option has been removed
   after being deprecated in favor of :kconfig:option:`CONFIG_PM_DEVICE_SYSTEM_MANAGED`.
 
+* The ``z_pm_save_idle_exit()`` PM API function has been removed.
+
 
 Deprecated APIs and options
 ===========================