Improve README documentation for clarity and usability

[hwii-florescent]

This PR improves the existing README documentation for the swift-2048 project. The following changes have been made to enhance clarity, usability, and developer experience:

• Added a detailed Overview section to explain the purpose of the project and what swift-2048 does.
• Included Installation Instructions to help users clone and run the project locally using Xcode.
• Expanded the Features section to highlight the main functionality of the app.
• Added a How to Play section for new users unfamiliar with the 2048 game mechanics.
• Improved the Contributing section with clear guidelines for submitting pull requests.
• Introduced a Bug Reports and Feedback section to direct users on how to report issues and submit feedback.
• Enhanced the Thoughts on Swift section with more detailed insights into the Swift language.
• Minor formatting improvements to make the README easier to read and navigate.

These changes aim to provide a more developer- and user-friendly README, making it easier for newcomers to understand the project and contribute to it.