dm: core: Add livetree documentation

Add some documentation for the live device tree support in U-Boot. This
was missing from the initial series.

Signed-off-by: Simon Glass <sjg@chromium.org>
Suggested-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Ɓukasz Majewski <lukma@denx.de>
1 file changed