Add microsoft-skill-creator skill

[TianqiZhang]

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

This PR adds the microsoft-skill-creator skill, that's a meta-skill that helps people create skills that teach AI agents about a certain Microsoft technology, product or service.

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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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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

Adds a new microsoft-skill-creator Agent Skill to help users generate other Microsoft-technology-focused skills, including a set of reusable skill templates and an entry in the skills registry docs.

Changes:

• Added microsoft-skill-creator skill instructions and workflow in SKILL.md
• Added reusable Microsoft skill templates in references/skill-templates.md
• Registered the new skill in docs/README.skills.md

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
skills/microsoft-skill-creator/SKILL.md	Defines the meta-skill’s purpose and end-to-end process for investigating a Microsoft technology and generating a new skill.
skills/microsoft-skill-creator/references/skill-templates.md	Provides copy/paste templates for different Microsoft technology categories (SDK, Azure service, framework, API).
docs/README.skills.md	Adds the new skill to the published skills index and lists its bundled reference asset.

[aaronpowell]

Left some comments and there's one from Copilot that I think is relevant