Fix GENERATE.md link broken issue and add CONTRIBUTING-CN.md for Chinese relevant contributors

[Binlogo]

• [x] Read CONTRIBUTING.md
• [x] Only edited files inside source folder (IMPORTANT) and commited them with a meaningful message
• [x] Ran generate-playground.sh, no errors
• [x] Opened playground, it worked fine
• [x] Did not commit the changes caused by generate-playground.sh
• [x] Linked to and/or created issue
• [x] Added a description to PR

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• link update: GENERATE.md -> CONTRIBUTING.md Fix #127
• add CONTRIBUTING-CN.md: describe how to contribute to Chinese translation and relevant branch descriptions.