Readme Improvments

[mehdie79]

I have done the following to improve the readability and design of the readme:

• Added a project logo (I hope you like it !)
• Added a short description below the logo for introducing the project to the user
• Added a table of content to make the navigation between sections easier
• Reorganized the sections by putting the "Motivation" section after the project intro. I think this will help by improving the structure of README.
• Added a License section for following the best practices.

Hope these changes help!