Fixes [YOCTO #9707]
* Replaced gummiboot with systemd-boot in the dev-manual
* Replaced the gummiboot class with a new systemd-boot class
* Replaced the appropriate gummiboot variables in the glossary
with new variables SYSTEMD_BOOT_CFG, SYSTEMD_BOOT_ENTRIES,
and SYSTEMD_BOOT_TIMEOUT.
(From yocto-docs rev: 778b620e65cc68531b3c41aeb8f27f2a07eb0d00)
Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>