Pin, Unpin, and why Rust needs them

What this post added

This post introduces and explains Rust's `Pin` and `Unpin` types, detailing their necessity for safely handling self-referential types and futures in asynchronous programming. It covers the concept of Futures, the dangers of self-referential types leading to memory unsafety, and how `Pin` and `Unpin` provide a safe mechanism for managing these types, particularly in the context of async Rust libraries.