Update README.md

Dear Davidbuechi, 
I am very happy, that I have found this programm. It works, so I can switch on my heating via Internet. Isn't it, great? So thank you a lot as it is above my programming abilities.

I have only two comments where I got stucked.
A) usb.h library
B) sudo priviledges
C) dmesg - whather is was found by system (lubuntu 13.10.
I hope that this small contribution can help your work.
Sincerely
xerostomus@seznam.cz
Merge pull request #2 from xerostomus/patch-1

Update README.md