Rename wks for systemd-boot per the suggestion from community.
Also amend description to distinguish it from others when
running "wic list images".
(From OE-Core rev: 6303dbbaa08214a37caf38e3b6b5a30a108bd3b7)
Signed-off-by: Jianxun Zhang <jianxun.zhang@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
