Update README with new development location (#1038)

Author: weshaggard

README.md

@@ -1,3 +1,7 @@
+>[!NOTE]
+>Active development has moved to [microsoft/mcp](https://github.com/microsoft/mcp) as of August 25, 2025
+
+
 # 🌟 Azure MCP Server
 
 The Azure MCP Server implements the [MCP specification](https://modelcontextprotocol.io) to create a seamless connection between AI agents and Azure services.  Azure MCP Server can be used alone or with the [GitHub Copilot for Azure extension](https://marketplace.visualstudio.com/items?itemName=ms-azuretools.vscode-azure-github-copilot) in VS Code.  This project is in Public Preview and implementation may significantly change prior to our General Availability.