docs: add UPGRADING.md template

[MSalopek]

Description

Add a template for upgrade instructions.

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Author Checklist

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• included the correct docs: prefix in the PR title
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• Confirmed the correct docs: prefix in the PR title
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• Reviewed content for spelling and grammar
• Tested instructions (if applicable)

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.