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

Documentation/translations/zh_CN/dev-tools/index.rst

@@ -19,13 +19,13 @@
    :maxdepth: 2
 
    gcov
+   kasan
 
 Todolist:
 
  - coccinelle
  - sparse
  - kcov
- - kasan
  - ubsan
  - kmemleak
  - kcsan