docs/zh_CN: add translations in zh_CN/dev-tools/kasan

Add new zh translations
* zh_CN/dev-tools/kasan.rst
and link it to zh_CN/dev-tools/index.rst

Reviewed-by: Fangrui Song <maskray@google.com>
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/20210603141127.101689-1-wanjiabing@vivo.com


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