Update c.ts adding certificates.dev

[alcfeoh]

Pull Request Template

Please ensure all items below are checked before creating a pull request:

• My changes were made in the resources folder, not in the auto-generated README.md file or db folder
• The resource is highly or exclusively related to programming and development
• My submission is formatted according to the guidelines in the contributing guide
• My submission is ordered alphabetically based on the resource name
• My submission has a useful description
• I have searched the repository for any relevant issues or pull requests

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Summary by cubic

Added Certificates.dev to the resources list to help developers find recognized frontend certification exams for Vue, React, Angular, Nuxt, and JavaScript. Placed alphabetically in resources/c.ts with description, keywords, categories, and URL.

^{Written for commit 2a4d7d8. Summary will update automatically on new commits.}

[github-actions]

New resource link: https://certificates.dev/

[cubic-dev-ai]

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