docs/zh_CN: core-api: Update translation of workqueue.rst to 6.9-rc1

Significant changes have been made to workqueue, and there are staging
works transferring from tasklet, while the current translation doesn't
include description around WQ_BH, an update seems to be helpful.

Synchronize translation from upstream commit 3bc1e711
("workqueue: Don't implicitly make UNBOUND workqueues w/ @max_active==1 ordered")
Signed-off-by: Xingyou Chen <rockrush@rockwork.org>
Signed-off-by: Tejun Heo <tj@kernel.org>