docs: expand package README with comprehensive documentation

[Copilot]

This PR significantly expands the package documentation by creating a comprehensive README file specifically for the NetEvolve.CodeBuilder package, following the structure and style guidelines from the extensions.data repository reference.

What was added

Created a new README.md file in the root directory that provides:

• Complete package overview with clear value proposition and key benefits
• Comprehensive feature documentation covering automatic indentation, performance optimizations, conditional code generation, XML documentation support, and memory-efficient operations
• Multiple installation methods including .NET CLI, Package Manager Console, and PackageReference formats
• Detailed usage examples progressing from basic to advanced scenarios
• Real-world code generation examples for classes, methods, and interfaces
• Complete API reference with organized method categories and detailed descriptions of all available methods and overloads
• Professional presentation with badges, proper formatting, and consistent structure

Key improvements

The package README provides developers with:

• Step-by-step examples showing how to generate properly indented C# code
• Advanced features demonstration including conditional appending, format support, and XML documentation generation
• Performance guidance with capacity management and memory-efficient operations
• Practical scenarios that developers commonly encounter in code generation tasks
• Complete method reference organized by functionality, including all method overloads for different data types (string, bool, char, char[], ReadOnlyMemory, unsafe char*), conditional methods, format methods, and XML documentation methods
• Accurate indentation documentation clarifying that indentation is handled automatically when appending brace/bracket characters

This documentation enhancement makes the NetEvolve.CodeBuilder package much more accessible to new users while providing comprehensive reference material for advanced usage scenarios.

Fixes #10.

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[Copilot]

Pull Request Overview

This PR creates comprehensive documentation for the NetEvolve.CodeBuilder package by adding a detailed README.md file that provides complete usage examples, API reference, and feature documentation. The documentation follows professional standards with proper formatting, badges, and structured sections.

Key changes:

• Adds comprehensive package overview with features, installation methods, and usage examples
• Includes detailed API reference covering all available methods and overloads
• Provides real-world code generation examples for classes, methods, and interfaces