boards: shields: arduino_giga_display_shield: docs: Fix docs.

Fix the board name.

Signed-off-by: Ibrahim Abdalkader <i.abdalkader@gmail.com>

Author: iabdalkader

boards/shields/arduino_giga_display_shield/doc/index.rst

@@ -40,7 +40,7 @@ for projects utilizing this shield. For example:
 
 .. zephyr-app-commands::
    :zephyr-app: samples/subsys/display/lvgl
-   :board: arduino_giga_r1_wifi
+   :board: arduino_giga_r1/stm32h747xx/m7
    :shield: arduino_giga_display_shield
    :goals: build