Edit BOM to reflect transistor T1

According to the datasheet for the BC846CMTF and the schematic,
In the BOM located in README.md, the line

1x PNP BPJ transistor, SOT-23 (BC846CMTF)

should state

1x NPN BJT transistor, SOT-23 (BC846CMTF)
Merge pull request #1 from bafeigum/Edit-README

Edit BOM to reflect transistor T1