Move --printUnusedTemplates in hugo scripts

[XhmikosR]

Description

Motivation & Context

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Live previews

• https://deploy-preview-{your_pr_number}--twbs-bootstrap.netlify.app/

Related issues

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@julien-deramond LGTY? Generally, we should try to not add new scripts if we can get away with the existent ones, because the list is already too long :)

[julien-deramond]

LGTM :). As long as we can have the info with the "serve" and/or "build" commands, I'm good with it.