prod/doc/analysis.hmac: added atrf-xtal measurement on atusb; clarifictions
prod/doc/analysis.hmac: added atrf-xtal measurement on atusb; clarifictions

cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan