[l10n] Improve Chinese (zh-CN) locale

[lawvs]

This PR adds the missing translation for the Chinese (zh-CN) locale - #3211.

• I have followed (at least) the PR section of the contributing guide.

[mui-bot]

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• Verify if the PR title respects the release format. Here are two examples (depending if you update or add a locale file)

  [l10n] Improve Swedish (sv-SE) locale
  [l10n] Add Danish (da-DK) locale

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