Update README.md

[pierridotite]

This commit overhauls the README to improve clarity, usability, and professionalism. Key updates include:

Enhanced Introduction: Clearly defines Monolith's purpose and highlights its strengths (e.g., collisionless embedding tables, real-time training). Key Features Section: Lists and explains the unique capabilities of the framework. Improved Setup Instructions: Detailed, step-by-step guide for installation, environment setup, and building the project. Documentation and Community: Links to tutorials, API guides, and community channels (Discord, GitHub Issues). Contributing Section: Simple guidelines for contributing with steps to submit pull requests. Style and Grammar Fixes: Corrected typos and ensured consistent formatting for better readability.

These changes make the README more accessible, professional, and engaging for both users and contributors, positioning Monolith as a leading framework for recommendation systems.