imx8mn_var_symphony: Add pending hardware support section

This board is in early stage development. Document pending support.

Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>

content/reference_hardware/imx8mn_var_symphony_setup.md

@@ -68,3 +68,11 @@ as it allows a common Apertis image to be programmed onto the SD card.
 - Set the Boot Select Switch (SW3) to INT (eMMC/NAND) instead of SD (micro SD
   card).
 - Insert the SD card and power up the Variscite Symphony board.
+
+# Pending hardware support for this board:
+
+This board is in early stage development. Support might not be complete for the
+following hardware components:
+
+* Display
+* Touchscreen