Add dutch i18n file

[DjSlash]

Pull Request type

Please check the type of change your PR introduces:

• [ ] Bug-fix
• [x] Feature (functionality, design, translations, etc.)
• [ ] Documentation change
• [ ] Project management (tests, CI, GitHub configuration, etc.)
• [ ] Other (please describe):

Current state

There's no Dutch translation file.

Proposed changes

Adding it.

Checklist

• [x] Bug-fixes and new features: I have tested locally with the latest release of Hugo extended. This requirement is a standard.
• [ ] Bug-fixes, new features, and doc changes: I have updated the relevant documentation as part of this PR.
• [x] All PRs: I have signed off (using git commit -s ...), or if not possible due to developer environment constraints, will comment below confirming that I am adhering to the Developer Certificate of Origin.

[onweru]

@DjSlash, thanks for the contribution. Please sign the commit (DCO), and I'll merge.

[DjSlash]

Hi, I've spent way too much time in trying to rebase the commit and I could not get it to work. Is it enough that I state it here in the comment?

Signed-off-by: Rutger van Sleen git@djslash.org