Should we rename `zh` to `zh-CN` and add `zh-TW` for Traditional Chinese support?

Is your feature request related to a problem? Please describe.

I would like to contribute Traditional Chinese (zh-TW) translation to this project. However, I noticed that the current Chinese translation uses zh as the language code in the file structure, while lang-list.json uses locale-zh-CN.

Describe the solution you'd like

To better follow language standards and avoid confusion, I suggest:

1. Rename existing files:

   • zh.json → zh-CN.json
   • HelpDoc/zh/ → HelpDoc/zh-CN/
   • Update lang-list.json: "locale-zh-CN": { "defaultMessage": "简体中文" }

2. Add new Traditional Chinese translation:

   • Create zh-TW.json
   • Create HelpDoc/zh-TW/ folder with translated documentation
   • Add to lang-list.json: "locale-zh-TW": { "defaultMessage": "繁體中文" }

Describe alternatives you've considered

Keep the existing zh folder structure and only add zh-TW files, but this would be inconsistent with the naming in lang-list.json which already uses locale-zh-CN.

Additional context

• Current file structure uses zh but lang-list.json already defines locale-zh-CN
• Other languages follow the pattern of language-COUNTRY code (e.g., en-US, ja-JP, ko-KR)
• This change would align with BCP 47 language tag standards

I'm happy to help with the translation work once we decide on the approach. Thank you!

Review lang-list.json, zh.json, and the HelpDoc/zh/ directory to map the current Chinese locale references before deciding how the rename affects the file structure. Done means the Simplified Chinese paths and locale entry use zh-CN, Traditional Chinese has zh-TW files and documentation, and both locale entries are consistent.