GitHub Copilot's starts supporting AGENTS.md: A step toward unified AI Instructions

GitHub Copilot now supports AGENTS.md, a unified format for configuring AI coding assistants. This addresses the fragmentation problem where different AI tools required separate configuration files like .cursorrules, CLAUDE.md, and .github/copilot-instructions.md. The implementation allows both root-level and nested AGENTS.md files for project-wide and context-specific instructions, while maintaining backward compatibility with existing formats. This move positions AGENTS.md as a potential standard for AI agent configuration across tools.