Rust Playground Exploration with mdbook

# Introduction

In this lab, you will learn about the Rust Playground, a web interface that allows you to experiment with Rust code. You will also discover how to use it with `mdbook` to make code examples playable and editable. Additionally, you will explore how to use it with docs and enable the "Run" button by using the `html_playground_url` attribute in Rust code.

> **Note:** If the lab does not specify a file name, you can use any file name you want. For example, you can use `main.rs`, compile and run it with `rustc main.rs && ./main`.