Add more skills and MCP section

[colbytimm]

This pull request updates the README.md to expand and clarify documentation around Copilot Agents, agent skills, and introduces a new section on MCPs (Model Context Protocols). The changes improve organization, add new examples, and provide clearer guidance on customizing Copilot.

Key documentation improvements:

• Updated section titles and introductory text to refer to "Copilot Agents" instead of "Copilot Instructions" and clarified the explanation of how to customize Copilot, including updated links to relevant documentation. [1] [2]
• Added a new "Skill Creator" agent skill example to the skills list, highlighting the ability to create and improve skills.

Expanded skill and integration listings:

• Added new categorized sections for "Cloud" and "Development" agent skills, including examples like Az CLI, Azure Prices, Playwright CLI, Frontend Design, and Webapp Testing.
• Introduced a new "MCPs" section, listing general, development, and cloud MCPs such as Knowledge Graph Memory, Filesystem, Fetch, Sequential Thinking, GitHub, Time, Playwright, Context7, Azure MCP, AWS Documentation, and gcloud.