Documentation/core-api : fix typo in workqueue

Correct to “boundaries” from “bounaries”

Signed-off-by: Attreyee Mukherjee <tintinm2017@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20231223175316.24951-1-tintinm2017@gmail.com