Update tiếng việt transaction-fees.md

[ngoccha]

Update the Vietnamese version for learn/transaction-fees/ section.

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[scott-klaytn]

@ngoccha Thank you for contributing to Klaytn docs. If you have something to add or improve Klaytn docs for other languages than English, you are expected to do it using Crowdin platform.

You can find and edit the Vietnamese version of this "transaction fee" page in the relevant Crowdin page. (Signup and login required)

FYI, we had a Transaction Fee page translation (partially translated) already but due to a recent structural change, it reverted to untranslated status in Crowdin. You can refer to the original Vietnamese page of "transaction fee" here and continue to complete the translation in Crowdin.

Thanks again.

[scott-klaytn]

This update is to be merged into main by #687