[hpsdr] Updating the ATLAS docs.

[Alex]

As a first task at updating the documentation, here's a couple questions on the ATLAS bus. 
I read the excel file (Atlas_Bus_Defs.xls) and the PDF file (Atlas_docs.pdf):

SPI bus is on pins C18-C25, C27, C29
JTAG is on pins A22-A25, A27, A29
I2C bus is on pins A20 & A21

If A2-A19 + A31 are the XBus and C2-C17 + C31 are the YBus, which lines are data and which are address lines?

I will update the documentation and post an updated version.

Alex, N3NP