docs: update Copilot SDK skill that reorganize language-specific guides for .NET, Go, Python, and TypeScript

[doggy8088]

Pull Request Checklist

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

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Description

Optimize agent skill structure.

closes #842

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Type of Contribution

• New instruction file.
• New prompt file.
• New agent file.
• New plugin.
• New skill file.
• New agentic workflow.
• Update to existing instruction, prompt, agent, plugin, skill, or workflow.
• 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 PR restructures the copilot-sdk skill documentation by moving language-specific implementation guidance into dedicated reference files (TypeScript/Node.js, Python, Go, .NET) while keeping SKILL.md focused on high-level concepts and resources.

Changes:

• Added language-specific guides under skills/copilot-sdk/references/ for TypeScript, Python, Go, and .NET.
• Simplified skills/copilot-sdk/SKILL.md by removing embedded per-language examples and updating the resources section.
• Updated docs/README.skills.md to list the new copilot-sdk reference files as bundled assets.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
skills/copilot-sdk/references/typescript.md	New TypeScript/Node.js reference guide (examples, streaming, tools, MCP, etc.).
skills/copilot-sdk/references/python.md	New Python reference guide with examples and recommended answer patterns.
skills/copilot-sdk/references/go.md	New Go reference guide with setup and usage examples.
skills/copilot-sdk/references/dotnet.md	New .NET/C# reference guide with SDK usage examples.
skills/copilot-sdk/SKILL.md	Refocused skill doc to high-level guidance; removed language-specific sections; updated resource links.
docs/README.skills.md	Added the new copilot-sdk reference files to the skill’s bundled assets list.