Add comprehensive documentation in README.md file

[Copilot]

This PR adds comprehensive documentation to the NextGen Widget AI Training repository through a detailed README.md file that serves as both an AI training resource and developer guide.

Problem Statement

The repository contained extensive training materials spread across multiple text files but lacked a central documentation entry point that would help users understand the repository's purpose, structure, and how to effectively use the training materials.

Solution

Created a comprehensive README.md that provides:

📖 Complete Documentation Structure

• Repository Overview: Clear explanation of the repository's role in AI training for NextGen UGC widget development
• File Structure Guide: Detailed breakdown of all 12 training files (components.txt, guides.txt, sdk.txt, etc.) and their specific purposes
• Widget Types Reference: Documentation for Grid, Carousel, Waterfall, Story, and Blank Canvas widgets with use cases

🤖 AI Training Focus

• Training Objectives: Specific guidelines for AI assistant behavior when helping with widget development
• Context Understanding: Documentation of Shadow DOM environment, widget lifecycle, and template systems
• Use Case Support: Covers both Front-End Engineers and Customer Support Managers with appropriate code examples
• Best Practices: Emphasis on blankcanvas template usage and SDK-based solutions

🔧 Technical Implementation

• Component Library: Complete reference for all available components (<tile-content>, <add-to-cart>, <shopspot-icon>, etc.) with TypeScript examples
• API Reference: Comprehensive SDK method documentation including tile operations, event management, and state management
• Code Examples: Real-world implementation patterns in TypeScript, Handlebars, and SCSS
• Getting Started Guide: Step-by-step setup instructions with prerequisites and basic widget configuration

📚 Developer Resources

• Troubleshooting Section: Common issues like Shadow DOM problems, component loading failures, and debug techniques
• Performance Best Practices: Lazy loading, CSS optimization, and accessibility guidelines
• Contributing Guidelines: How to improve and extend the training materials

Quality Improvements

Addressed code review feedback by:

• Updated Node.js requirement from 16+ to 18+ (current LTS)
• Fixed repository structure tree to accurately reflect actual files
• Removed broken references to non-existent LICENSE and package.json files
• Ensured all badges and links point to valid resources

The documentation now provides a single source of truth for understanding and utilizing this AI training repository, making it easier for both AI systems and human developers to work with NextGen UGC widgets effectively.

Original prompt

Add some comprehensive documentation in a README.md file

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[oliverkuchies]

@copilot Remove references to licensing