Sync the spelling.txt file with a recent version of the one found in
Linux kernel.
List sorting was preserved (however inconsistent it might be) to
simplify future syncs.
Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>
Somehow this is seems to be a very common typo. Adding it to spelling.txt
to catch it as part of compliance check.
Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>
