boards/stk3600: fix broken links
boards/stk3600: fix broken links

OTAkeys/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,yogo1212/RIOT,yogo1212/RIOT,OlegHahm/RIOT,jasonatran/RIOT,miri64/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,ant9000/RIOT,kYc0o/RIOT,yogo1212/RIOT,ant9000/RIOT,OTAkeys/RIOT,basilfx/RIOT,kYc0o/RIOT,miri64/RIOT,yogo1212/RIOT,ant9000/RIOT,basilfx/RIOT,kaspar030/RIOT,authmillenon/RIOT,basilfx/RIOT,yogo1212/RIOT,OlegHahm/RIOT,basilfx/RIOT,ant9000/RIOT,miri64/RIOT,authmillenon/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,miri64/RIOT,yogo1212/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,authmillenon/RIOT,authmillenon/RIOT,OTAkeys/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,kaspar030/RIOT,OTAkeys/RIOT,jasonatran/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,authmillenon/RIOT,miri64/RIOT,kYc0o/RIOT,ant9000/RIOT,basilfx/RIOT