USBKeyboard example

The example emulates keyboard over USB port.

1. Flash the board, and ensure the target's auxiliary USB is plugged into the PC.
2. Reset the target.
3. "Hello World" sequence should be typed by the virtual keyboard in loop with 1 sec delays.

MIRRORED FROM MASTER EXAMPLE SNIPPETS REPOSITORY: mbed-os-examples-docs_only. ANY CHANGES MADE DIRECTLY TO THIS REPOSITORY WILL BE AUTOMATICALLY OVERWRITTEN.