x86: Add a README.x86 for U-Boot on x86 support

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
(Use 'Link' as the name for the Chromebook Pixel consistently)

Change-Id: I158c88653978ff212334f6d4ffeaf49fa81baefe
1 file changed