doc: matter: add note on openthread memory configuration

Mention openthread memory configuration in matter docs.

Signed-off-by: Adrian Gielniewski <[email protected]>

Author: adigie

doc/nrf/protocols/matter/getting_started/memory_optimization.rst

@@ -417,6 +417,10 @@ To use a dynamic heap size on your Matter device, set them both to ``n``.
 The static heap size means that you can define the maximum heap size for your application by setting the :kconfig:option:`CONFIG_CHIP_MALLOC_SYS_HEAP_SIZE` Kconfig value.
 You can also adjust the heap dedicated for MbedTLS purposes by setting the :kconfig:option:`CONFIG_MBEDTLS_HEAP_SIZE` Kconfig option value.
 
+.. note::
+   The Thread protocol has a separate configuration for memory allocation.
+   See :ref:`thread_configuring_messagepool` in the Thread documentation for more information.
+
 Memory profiling troubleshooting
 ================================