docs/zh_CN/rust: Update the translation of coding-guidelines to 6.9-rc4

Update to commit bc2e7d5c ("rust: support `srctree`-relative links")

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/e83b5dd929371d42889b19750e5e0385544e170f.1714113680.git.siyanteng@loongson.cn