Update BOM or Build Instructions for pre-soldered Xiao

[nakkamarra]

After building two myself, one where I trimmed the wires from the screen and spliced between the proximity / ambient light sensor board and soldered to the xiao and one where I didn't use the ambient light sensor, It's worth calling out that a pre-soldered xiao [image] will fit well and allow using the pre-attached pins from the screen in the case of assembling without ambient light sensor. I think this offers a much simpler and cleaner build option for those who don't care for the extra feature of the light sensor