Updated README.md file to include supporting links and more detail to sections

[carboitel]

This PR contains edits to the README file so that core concepts in the documentation can be more easily accessed and understood. I specifically added the following updates to help improve the documentation and contribution efforts of the program:

• Added a table of contents
• Updated Clendar's description to be more informative for new users
• Added supporting links to the tech stacks
• Created a step-by-step list of how to contribute to the application
• Added a section of important files to navigate to
• Updated the inspiration credits since the git page link no longer existed

[vinhnx]

Looks really good, thank you so much @carboitel ! 🙌