README: change reference from LinuxBIOS to coreboot

The linuxbios.org website does not exist anymore, so point the reader towards
coreboot.org instead.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Resolves: https://github.com/openbios/openbios/issues/17
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
1 file changed