galileo: Add README file
galileo: Add README file

This patch adds a README file which contains general information about
the Intel Galileo board support. The file provides information about
supported features as well as instructions on how to build, run and debug
applications for this platform.

MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,arurke/contiki,arurke/contiki,MohamedSeliem/contiki,arurke/contiki,MohamedSeliem/contiki,arurke/contiki,arurke/contiki,arurke/contiki,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki