doc: changelog: mention nRF54LM20 support in the nRF Desktop application

Added information to the changelog that describes the nRF54LM20 DK
support in the nRF Desktop application.

Ref: NCSDK-34043

Signed-off-by: Kamil Piszczek <[email protected]>

Author: kapi-no

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

@@ -210,7 +210,10 @@ nRF5340 Audio
 nRF Desktop
 -----------
 
-|no_changes_yet_note|
+* Added application configurations for the :zephyr:board:`nrf54lm20dk` board.
+  The configurations are supported through the ``nrf54lm20dk/nrf54lm20a/cpuapp`` board target.
+  For details, see the :ref:`nrf_desktop_board_configuration` page.
+  The :zephyr:board:`nrf54lm20dk` board support is experimental.
 
 nRF Machine Learning (Edge Impulse)
 -----------------------------------