doc: Matter: Add a guide for custom board creation

A new guide is added to each sample and contains
instruction on how to create a custom board and prepare it
to work with Matter.

Signed-off-by: Arkadiusz Balys <arkadiusz.balys@nordicsemi.no>

Author: ArekBalysNordic

doc/nrf/includes/advanced_conf_matter.txt

@@ -23,3 +23,8 @@ Factory data support
 .. include:: ../lock/README.rst
     :start-after: matter_door_lock_sample_factory_data_start
     :end-before: matter_door_lock_sample_factory_data_end
+
+Custom board with Nordic SoC
+----------------------------
+
+.. include:: /includes/matter_custom_board.txt

doc/nrf/includes/matter_custom_board.txt

@@ -0,0 +1,21 @@
+.. toggle::
+
+   To prepare the sample to work with a custom board, complete the following steps:
+
+      1. Refer to the :ref:`create-your-board-directory` Zephyr guide and create your board directory.
+      #. Modify the contents of the :file:`board.yaml` file according to the :ref:`board_description` user guide.
+      #. Update the :ref:`default_board_configuration` (all `.dts` and `.dtsi` files) to match your board's requirements.
+      #. Write Kconfig files to enable all required Kconfig options for your board.
+      #. If you want to build your custom board with nRF70 Wi-Fi support, set the :kconfig:option:`CONFIG_CHIP_WIFI` and :kconfig:option:`SB_CONFIG_WIFI_NRF70` Kconfig options to ``y``.
+      #. If your device uses external flash, add its devicetree definition under the :file:`board/<board_name>_<soc_name>.overlay` file, and set ``nordic,pm-ext-flash`` in the devicetree's ``chosen`` configuration.
+      #. Refer to the :ref:`ug_matter_device_advanced_kconfigs` user guide, create your list of advanced configurations for your board, and apply the selected Kconfig options in the :file:`prj.conf` file.
+      #. See the :ref:`list of threads used in Matter application <matter_threads_table>` and adjust stack sizes according to your board and project requirements.
+      #. A custom board does not have support for LEDs and buttons by default.
+         Therefore, you need to provide your own implementation of the :file:`nrf/samples/matter/common/src/board/board.cpp` board file.
+
+   For more information, see the following guides:
+
+      * :ref:`board_porting_guide` and :ref:`custom_board_definition` to learn how to create a custom board directory.
+      * :ref:`ug_matter_device_optimizing_memory` to learn how to optimize memory on your board.
+      * :ref:`ug_matter_device_advanced_kconfigs` to learn about Matter configuration.
+      * :ref:`ug_matter_hw_requirements` to learn about hardware requirements for Nordic Development Kits and to use as a reference when planning your custom board.

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

@@ -484,6 +484,7 @@ Matter samples
 
   * The :ref:`matter_temperature_sensor_sample` sample that demonstrates how to implement and test a Matter temperature sensor device.
   * The :ref:`matter_contact_sensor_sample` sample that demonstrates how to implement and test a Matter contact sensor device.
+  * The ``matter_custom_board`` toggle paragraph in the Matter advanced configuration section of all Matter samples that demonstrates how add and configure a custom board.
 
 * Updated all Matter over Wi-Fi samples and applications to store a portion of the application code related to the nRF70 Series Wi-Fi firmware in the external flash memory by default.
   This change breaks the DFU between the previous |NCS| versions and the |NCS| v3.2.0.