docs/zh_CN: Add sak index Chinese translation

Translate lwn/Documentation/security/sak.rst into Chinese

Update the translation through commit 4d3beaa0
("docs: security: move some books to it and update")

Reviewed-by: Yanteng Si <si.yanteng@linux.dev>
Reviewed-by: Alex Shi <alexs@kernel.org>
Signed-off-by: zhangwei <zhangwei@cqsoftware.com.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250110100405.2225-1-zhangwei@cqsoftware.com.cn