USB stick installation using wget fails

[Daniel Gitu]

I'm trying to install guixsd from the manual but On running the wget 
command I'm getting No such file ‘guixsd-usb-install-0.12.0.system.xz.sig’.

I've gone through the help mailing list for a previous solution as well 
as googled and have found no solution. What am I missing?

Regards,

Dan