README: Update url of documentation
README: Update url of documentation


OTAkeys/RIOT,jasonatran/RIOT,jasonatran/RIOT,authmillenon/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,authmillenon/RIOT,kaspar030/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,ant9000/RIOT,authmillenon/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,miri64/RIOT,kYc0o/RIOT,miri64/RIOT,kYc0o/RIOT,jasonatran/RIOT,jasonatran/RIOT,authmillenon/RIOT,OlegHahm/RIOT,ant9000/RIOT,OTAkeys/RIOT,miri64/RIOT,ant9000/RIOT,RIOT-OS/RIOT,ant9000/RIOT,miri64/RIOT,authmillenon/RIOT,miri64/RIOT,authmillenon/RIOT,ant9000/RIOT,kYc0o/RIOT,kaspar030/RIOT