doc: add README.md for GUI directory (#2021)

Added README.md for the Puter GUI with details on structure, development, contributing, and resources.

src/gui/README.md

@@ -0,0 +1,61 @@
+# Puter GUI
+
+This directory contains the frontend/GUI code for Puter's web-based operating system interface.
+
+## Overview
+
+The Puter GUI is a web-based desktop environment built with vanilla JavaScript. It provides a familiar desktop experience directly in your browser, including a taskbar, windows, file manager, and various built-in applications.
+
+## Directory Structure
+
+- `src/` - Main source code for the GUI
+- `doc/` - Documentation files
+  - `el0.md` - Documentation for the el0 utility
+  - `utils.md` - Documentation for utility functions
+  - `webpack_attempts.md` - Notes on webpack configuration
+- `webpack/` - Webpack configuration files
+
+## Development
+
+### Getting Started
+
+To run Puter locally with the GUI:
+
+```bash
+# From the project root
+npm install
+npm start
+```
+
+The GUI will be available at http://puter.localhost:4100 (or the next available port).
+
+For detailed setup instructions, see the main [README.md](../../README.md) in the project root.
+
+## Architecture
+
+The GUI follows these conventions:
+
+- **Code Style**: Uses standard whitespace conventions (see [CONTRIBUTING.md](../../CONTRIBUTING.md#style-changes))
+- **Modular Design**: Components are organized by functionality
+- **Event-Driven**: Utilizes a pub/sub pattern for component communication
+
+## Contributing
+
+Contributions to improve the GUI are welcome! Please:
+
+1. Read the main [CONTRIBUTING.md](../../CONTRIBUTING.md) guide
+2. Follow the existing code style in this directory
+3. Test your changes thoroughly in different browsers
+4. Keep PRs focused on a single feature or fix
+
+## Related Documentation
+
+- [Main Project README](../../README.md)
+- [Contributing Guidelines](../../CONTRIBUTING.md)
+- [Backend Documentation](../backend/CONTRIBUTING.md)
+
+## Resources
+
+- [Live Demo](https://puter.com)
+- [Discord Community](https://discord.com/invite/PQcx7Teh8u)
+- [Issue Tracker](https://github.com/HeyPuter/puter/issues)