docs/zh_CN: add damon usage translation

Translate .../admin-guide/mm/damon/usage.rst into Chinese.
Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/431f1c2a158c61a6556f58048cb54961ab7a8790.1646899089.git.siyanteng@loongson.cnSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/admin-guide/mm/damon/index.rst

@@ -20,9 +20,9 @@
    :maxdepth: 2
 
    start
+   usage
 
 Todolist:
 
 
-*   usage
 *   reclaim