docs: add zh-CN translation

[vanchKong]

commit about:

• add zh-CN translation, synced to 1.0.0-rc.29
• Add markdown basic usage documentation

translation details:

• At present, almost all translations are completed
• I'll follow up with updates to the docs （my own repository: vanchKong/VitePressCN & site）
• mostly machine translated
• A few add personal understanding
• The rest are unable to find a suitable translation，some are the original text, and some are displayed attaching the original text
• some work refers to this guy awxiaoxian2020

preview link
https://deploy-preview-2249--vitepress-docs.netlify.app/

[brc-dd]

Hi guys, thanks a lot for maintaining this! Is this ready to merge or are there any blockers/TODOs? If you guys are fine, we can merge this by this week. (we are planning to release v1 in few days)

[awxiaoxian2020]

@brc-dd I have checked these files to ensure the translations line by line with the English content, and we have over 10000 rows which is not perfect but can be improved by contributors easily. So on my side, This PR can be merged now.