Fix typos in documentation of Image.add_partition() and
Image.__format_disks().
(From OE-Core rev: f5bf7bf253224912c66bab89f48ff63a73e0d698)
Signed-off-by: Maciej Borzecki <maciej.borzecki@rndity.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>