📝 Add README file

Description

This pull request introduces the initial README.md file for the scikit-sampling project. This file serves as the primary entry point for new users and contributors, providing essential information about the library.

Key Additions

• Project Overview: A clear and concise description of scikit-sampling and its goals.
• Installation Guide: Simple instructions for installing the package via pip.
• Features List: Highlights the core functionalities, starting with the sample_size function.
• Usage Example: A practical code snippet demonstrating how to use the library, making it easy for users to get started.
• Project Badges: Includes badges for the GitHub repository, license, and build status, offering a quick and professional overview of the project's status.

This addition is a foundational step in making the project accessible and well-documented.