Updates to the readme

[zak-off-zak]

This pull request includes significant updates to the README.md file, transforming it from a generic CMake SFML project template to documentation specific to the Flappy-Plus-Plus game project. The most important changes include an overview of the project, implementation details, and instructions for building and running the game.

Project Overview and Implementation Details:

• The project is described as a recreation of the Flappy Bird game using SFML and C++. It utilizes a simplified version of the state pattern to manage game states (init, handle_input, update, and render methods) and a Game class to manage global variables, textures, fonts, and the main game loop.
• The Physics class models the behavior of physical objects using basic Newtonian laws of motion, used primarily in the Bird class to simulate realistic falling.
• Collision detection is implemented using SFML's functionality to check for overlapping rectangles, triggering game over conditions.

Building and Running Instructions:

• Instructions for installing the SFML library and building the project using make or cmake are provided, including commands for both methods.

References and Credits:

• The project credits the SFML-Template and assets by Kenney Vleugels, with links and license information provided. (F928b07aL