docs/zh_CN: Add siphash index Chinese translation

docs/zh_CN: Add siphash index Chinese translation

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

Update the translation through commit 12fe434314c8
("Documentation: siphash: Fix typo in the name of offsetofend macro")

Reviewed-by: Yanteng Si <si.yanteng@linux.dev>
Signed-off-by: zhangwei <zhangwei@cqsoftware.com.cn>
Reviewed-by: Yanteng Si <siyanteng@linux.dev>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/0af3d9b8be0e5166f74bd36fd6b040767f767fce.1736315479.git.zhangwei@cqsoftware.com.cn