docs: zh_CN: fix a broken reference

The location of the rust doc is wrong (probably a typo). Fix it.

Fixes: 3a591515 ("docs/zh_CN: Add translation zh_CN/doc-guide/kernel-doc.rst")
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/94fe771609d32583fee41f47fe29433cbce5b04e.1656234456.git.mchehab@kernel.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>