docs: zh_CN/vm/zsmalloc.rst: fix a typo

typo:
	zs_malloc.rst -> zsmalloc.rst

Fixes: 6dbc3a5b ("docs/zh_CN: add vm zsmalloc translation")
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Acked-by: Yanteng <Si&lt;siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/25a9fff20d39a6638b8a7c0fefa0767e77d96dec.1656234456.git.mchehab@kernel.org


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