Update README file

[osakellarides]

Updated project documentation, changes described as below:

• Added Table of Contents
• Shortened the description and split into two categories 'Description' & 'How to Use'
• Added 'How to Use' section to walk through how the application works. Added a more descriptive & relevant description walking through the entire application.
• Added 'How to Contribute' section for any people who want to contribute to this project in the future.
• Added 'Project Directory Structure' to show a simplified overview of how the project is laid out.
• Added 'Tech Stack' section to specify any tools/libraries commonly used throughout the application.