fix(i18n): improve Dutch(nl) translation

[JBtje]

Updated translations

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Description

I added the missing Dutch translations.

🤖 Generated by Copilot at 78bf273

Translated some UI texts to Dutch in packages/locale/lang/nl.ts. This improves the localization of the element-plus library for Dutch users.

Related Issue

No related issue as far as i know

Explanation of Changes

🤖 Generated by Copilot at 78bf273

• Translate the error, title, confirmButtonText and cancelButtonText properties of the Dutch language file (packages/locale/lang/nl.ts) from English to Dutch (link)

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