2nd Update request documentation Xol PCB

[neptunus0001]

https://github.com/ruiqimao/VoronStuff/tree/main/Xol_PCB

In chapter: Selectable fan voltage

I think it would be of value to update the documentation to something like:

There are two sets of solder jumpers, one for each type of fan, that should be bridged to select the fan voltage.

• Hotend fan = HEF
• Part cooling fan = PCF

Solder jumper HEF and PCF must be soldered closed with solder tin to select the voltage you would like to use.

Example:
To use 5 volts for the Part cooling fan close the purple block with solder tin.