Translate the following documents into Chinese:

- userspace-api/futex2.rst
Signed-off-by: Rui Li <me@lirui.org>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Wu XiangCheng <bobwxc@email.cn>
Link: https://lore.kernel.org/r/20221105041741.288094-1-me@lirui.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>