docs/zh_CN: add vm/index translation

Translate ../vm/index.rst into Chinese.
Signed-off-by: NYanteng Si <siyanteng@loongson.cn>
Reviewed-by: NTang Yizhou <tangyizhou@huawei.com>
Reviewed-by: NAlex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/60c579b34792c4c76194c4843a695263a982b37d.1641866889.git.siyanteng@loongson.cnSigned-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/index.rst

@@ -113,6 +113,7 @@ TODOList:
    sound/index
    filesystems/index
    scheduler/index
+   vm/index
 
 TODOList:
 
@@ -140,7 +141,6 @@ TODOList:
 * gpu/index
 * security/index
 * crypto/index
-* vm/index
 * bpf/index
 * usb/index
 * PCI/index

Documentation/translations/zh_CN/vm/index.rst

+.. include:: ../disclaimer-zh_CN.rst
+
+:Original: Documentation/vm/index.rst
+
+:翻译:
+
+ 司延腾 Yanteng Si <siyanteng@loongson.cn>
+
+:校译:
+
+=================
+Linux内存管理文档
+=================
+
+这是一个关于Linux内存管理（mm）子系统内部的文档集，其中有不同层次的细节，包括注释
+和邮件列表的回复，用于阐述数据结构和算法的基本情况。如果你正在寻找关于简单分配内存的建
+议，请参阅(Documentation/translations/zh_CN/core-api/memory-allocation.rst)。
+对于控制和调整指南，请参阅(Documentation/admin-guide/mm/index)。
+TODO:待引用文档集被翻译完毕后请及时修改此处）
+
+.. toctree::
+   :maxdepth: 1
+
+
+TODOLIST:
+* active_mm
+* arch_pgtable_helpers
+* balance
+* damon/index
+* free_page_reporting
+* frontswap
+* highmem
+* hmm
+* hwpoison
+* hugetlbfs_reserv
+* ksm
+* memory-model
+* mmu_notifier
+* numa
+* overcommit-accounting
+* page_migration
+* page_frags
+* page_owner
+* page_table_check
+* remap_file_pages
+* slub
+* split_page_table_lock
+* transhuge
+* unevictable-lru
+* vmalloced-kernel-stacks
+* z3fold
+* zsmalloc