reference_hardware: Add iMX8MN Variscite Symphony board documentation

Related LAVA docs side https://gitlab.collabora.com/lava/docs/-/merge_requests/22/

content/reference_hardware/arm64.md

@@ -29,4 +29,5 @@ If you currently don't have access to any of the below supported hardware, the
 | Alternative ARM64 reference device | [Renesas R-Car M3-W Salvator-X (r8a7796-salvator-x)](http://elinux.org/R-Car/Boards/Salvator-X) | [Setup guide]( {{< ref "/reference_hardware/rcar-gen3_setup.md" >}} ) **Untested** |
 |                                    |                                                                                                 |                                                                            |
 | Alternative ARM64 reference device | [Raspberry Pi 4 model B](https://www.raspberrypi.org/products/raspberry-pi-4-model-b/)          | [Setup guide]( {{< ref "/reference_hardware/rpi4_setup.md" >}} )           |
+| Alternative ARM64 reference device | [i.MX8MN Variscite Symphony board](https://www.variscite.com/product/evaluation-kits/var-som-mx8m-nano-evaluation-kits/) | [Setup guide]( {{< ref "/reference_hardware/imx8mn_var_symphony_setup.md" >}} ) |