Documentation file for DFU extension. With this functionality it is now
possible to transfer FIT images with firmware updates via TFTP and use
DFU backend for storing them.
Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
