Update Klipper Expander Instructions

[Tharkus]

I'd like help with flashing the Klipper Expander Board.

The instructions are very old and different from the current ones.
Below are images of the current options, so I'm at a loss as to which ones to select.

https://github.com/VoronDesign/Voron-Hardware/blob/master/Klipper_Expander/Documentation/Setup_and_Flashing_Guide.md

Image in instructions in Set the "Optional features":

Image of the current configuration Set the "Optional features"

[mattjm]

I put in a PR to fix this and it has been merged: #241. Probably you have it figured out by now, but hopefully that helps others.