Improved itch.io page and added credits

TutTutVroomVroom itch.io's page has received some improvements :

🔶New Color theme

🔶New font (Quicksand)

🔶Keyboard and controller mapping diagrams

🔶All new screenshots

🔶New header

Hope it will be more readable.

I also added credits as a separate file (at the moment). It will be inserted inside the game on the next release.