applications: nrf_desktop: indicate the broken nRF54H20 DK target

Added a note to the nRF Desktop documentation to warn the user that
the nRF54H20 DK no longers works with this project.

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

Author: kapi-no

applications/nrf_desktop/board_configuration.rst

@@ -178,3 +178,9 @@ Sample mouse or dongle (``nrf54h20dk/nrf54h20/cpuapp``)
         For detailed information on working with the nRF54H20 DK, see the :ref:`ug_nrf54h20_gs` documentation.
       * The configurations use the Software Updates for Internet of Things (SUIT) and support firmware updates using the :ref:`nrf_desktop_dfu`.
         Configurations acting as HID peripherals also support firmware updates using the :ref:`nrf_desktop_dfu_mcumgr`.
+
+      .. note::
+         The nRF Desktop application does not build or run for the ``nrf54h20dk/nrf54h20/cpuapp`` board target due to the IronSide SE migration.
+         See the ``NCSDK-34299`` in the :ref:`known_issues` page for more information.
+         The :ref:`nrf_desktop` documentation may still refer to concepts that were valid before the IronSide SE migration (for example, to the SUIT solution).
+         The codebase and documentation will be updated in the future releases to address this issue.