[FEAT] - Improve overall project documentation and onboarding

[dylanlangston]

Is your feature request related to a problem? Please describe.

The project currently lacks comprehensive documentation, making it difficult for new contributors to understand the architecture, set up their development environment, and start contributing. Key projects like AvaloniaXKCD.Generators and AvaloniaXKCD.Exports are not well-documented, and there's no clear contribution guide.

Describe the solution you'd like

Improve overall documentation coverage to make the project welcoming and accessible. This includes:

• Expanding on README.md. Suggestions include:
  • "What is Axkcd?" section
  • Features overview
  • "Getting Started" guide
  • "Building from Source" instructions for each platform
• Improve the GitHub copilot documentation using resources like https://github.com/github/awesome-copilot
• Improve other LLM integration if appropriate.
• Specifically documenting the role of AvaloniaXKCD.Generators and AvaloniaXKCD.Exports projects
• Adding inline code comments in complex areas (especially in XKCDCore and CommandLineParser)
• Writing brief overviews for each major project in /src/
• Creating a CONTRIBUTING.md file outlining:
  • Pull request process
  • Branching strategy
  • Coding standards and conventions
  • Issue tagging guidelines
• Documenting how the ExplainXKCD client works
• Explaining interop with TypeScript functions in AvaloniaXKCD.Site/src/interop.ts
• Creating a docs/ folder for developer-focused documentation
• Adding "how to run tests" and platform-specific build instructions

Describe alternatives you've considered

• Relying solely on inline comments, but high-level architecture documentation is still needed.

Additional context

Acceptance Criteria:

• New contributors can follow the README and get a working build
• Core projects and their responsibilities are clearly documented
• Contribution and testing workflows are described
• Documentation encourages exploration and identifies areas for improvement

This is a perfect entry point for new contributors since documenting the project naturally involves exploring and understanding how it works. Contributors may uncover gaps or improvements that can become new issues.