bug(vcu): button connections not identified on silkscreen

### Description
Button connections are not labelled on the back silkscreen as shown in screenshot below (they are the top right 3 pins on the connector). Would be good to do it the same way as the LEDs.

<img width="411" alt="Screenshot 2023-04-16 at 23 21 38" src="https://user-images.githubusercontent.com/31595761/232345913-39e36869-b241-455c-a4cf-c44b91a0b1b6.png">
