Add agent-skills.instructions.md - Guidelines for creating Agent Skills

[yeelam-gordon]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• My contribution adds a new instruction, prompt, or chat mode 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, or chat mode with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.

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Description

This pull request adds comprehensive documentation for creating high-quality Agent Skills for GitHub Copilot. The main change is the introduction of a new guidelines file, which is now referenced in the main instructions README to help users and contributors understand how to structure, describe, and bundle resources for Agent Skills.

Documentation additions and improvements:

• Added a new instructions/agent-skills.instructions.md file containing detailed guidelines for Agent Skills, including directory structure, required metadata, best practices for writing descriptions, bundling resources, and validation checklists.
• Updated docs/README.instructions.md to include a reference and install badge for the new Agent Skills guidelines, making it discoverable alongside other team and project-specific instructions.

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Type of Contribution

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

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Additional Notes

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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.

[Copilot]

Pull request overview

This pull request introduces comprehensive documentation for creating Agent Skills for GitHub Copilot. Agent Skills are self-contained folders with instructions and resources that teach AI agents specialized capabilities through progressive loading.

Key changes:

• Added detailed guidelines file covering skill structure, metadata requirements, resource bundling, and best practices
• Updated the instructions README to include the new guidelines with install badges

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
instructions/agent-skills.instructions.md	New comprehensive guidelines file for Agent Skills, including frontmatter requirements, directory structure, progressive loading architecture, and validation checklists
docs/README.instructions.md	Added table entry with install badges for the new Agent Skills guidelines

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[yeelam-gordon]

@codemillmatt, not sure if you can help review this PR. Thanks in advance.