doc: matter: fix release notes changelog

Fix duplicated entry in release notes for matter

Signed-off-by: Maciej Baczmanski <[email protected]>

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -348,9 +348,6 @@ Keys samples
 Matter samples
 --------------
 
-* Updated all Matter samples that support low-power mode to enable the :ref:`lib_ram_pwrdn` feature.
-  It is enabled by default for the release configuration of the :ref:`matter_lock_sample`, :ref:`matter_light_switch_sample`, :ref:`matter_smoke_co_alarm_sample`, and :ref:`matter_window_covering_sample` samples.
-
 * Updated:
 
   * All Matter samples that support low-power mode to enable the :ref:`lib_ram_pwrdn` feature.