Add gh-runtime-cli extension example to gh-cli skill

[Copilot]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• My contribution adds a new instruction, prompt, agent, or skill file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, agent, or skill with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.

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Description

Adds github/gh-runtime-cli as a concrete extension installation example in the gh-cli skill. The runtime-cli extension deploys sparks to GitHub's runtime environment.

Changes:

• Added installation command for github/gh-runtime-cli in the Extensions section following existing generic example pattern

# Install GitHub runtime CLI extension
gh extension install github/gh-runtime-cli

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Type of Contribution

• New instruction file.
• New prompt file.
• New agent file.
• New collection file.
• New skill file.
• Update to existing instruction, prompt, agent, collection or skill.
• Other (please specify):

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Additional Notes

The gh-runtime-cli is an official GitHub CLI extension maintained by GitHub. Positioned between the generic owner/extension-repo example and the branch-specific installation to provide a real-world reference.

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By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.

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[Copilot]

Pull request overview

Updates the gh-cli skill documentation to include a concrete GitHub CLI extension install example (github/gh-runtime-cli) in the Extensions section.

Changes:

• Added an explicit example command to install the github/gh-runtime-cli extension alongside the existing generic extension install examples.

[Copilot]

This skill consistently uses placeholder repo names (e.g., owner/repo, owner/extension-repo) for commands. Adding a concrete repo here makes the examples inconsistent and may become stale/feel like an endorsement; consider keeping the command generic and (if needed) mentioning github/gh-runtime-cli as an inline comment or prose note rather than a dedicated install step.