Merge pull request #1246 from per1234/uno-r4-wifi-hid-upload-workaround

Document special upload procedure in UNO R4 WiFi HID tutorial

Author: jacobhylen

content/hardware/02.hero/boards/uno-r4-wifi/tutorials/usb-hid/usb-hid.md

@@ -36,7 +36,17 @@ To turn your board into an HID, you can use the **keyboard/mouse** API that is b
 - [Keyboard](https://www.arduino.cc/reference/en/language/functions/usb/keyboard/)
 - [Mouse](https://www.arduino.cc/reference/en/language/functions/usb/mouse/)
 
-In the section below, you will a couple of useful examples to get you started!
+## Sketch Upload Interference
+
+As a consequence of the multi-processor design of the UNO R4 WiFi board, uploads may fail with a "`No device found on ...`" error when the board is running a sketch that uses the HID capabilities.
+
+For this reason, you should use the following procedure to upload under these conditions:
+
+**1.** Press and release the button marked "**RESET**" on the board quickly twice. The LED marked "**L**" on the board should now be pulsing.
+
+**2.** Select the port of the board from the menu in Arduino IDE. The port might have changed after the previous step, so make sure to verify that it is selected.
+
+**3.** Upload your sketch as usual.
 
 ## Keyboard