Description notes 5v pins when recommending 3v3 pins

[jatmn]

https://github.com/VoronDesign/Voron-Documentation/blame/bf6cbd3932a58b8a57c8adf0fd72d003d9b2dc92/community/electronics/xbst_/PT100.md#L91

https://github.com/VoronDesign/Voron-Documentation/blame/bf6cbd3932a58b8a57c8adf0fd72d003d9b2dc92/community/electronics/xbst_/PT100.md#L103