chore: Improve sample keyword list for vacation calendar

[CraigHutchinson]

Description

The sample misses common UK keywords 'holiday', 'time off' and 'annual leave'

Fixes # (issue)

Is it been tested?

• Development testing done

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have performed a peer-reviewed with team member(s)
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

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[conventional-commit-lint-gcf]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot
https://conventionalcommits.org/

[CraigHutchinson]

@vinay-google I do not have riughts to set reviewers, cheers.