Update directions on where to place signals.cpp.
Update directions on where to place signals.cpp.

ene-ilies/vi-firmware,mgiannikouris/vi-firmware,openxc/vi-firmware,openxc/vi-firmware,openxc/vi-firmware,mgiannikouris/vi-firmware,ene-ilies/vi-firmware,ene-ilies/vi-firmware,mgiannikouris/vi-firmware,openxc/vi-firmware,mgiannikouris/vi-firmware,ene-ilies/vi-firmware