[Rust Roadmap] Add "iced" topic to "GUI Development" node

[Wesssed]

Roadmap URL

https://roadmap.sh/rust

Suggestions

#iced 
iced is a cross-platform GUI library for Rust. It is inspired by ELM, a delightful functional language for building web applications.
iced is strongly focused on simplicity and type-safety. As a result, iced tries to provide simple building blocks that can be put together with strong typing to reduce the chance of runtime errors.

[@official@iced](https://iced.rs/)
[@official@iced Guide](https://book.iced.rs/index.html)
[@articlel@Building a Modern Rust GUI with Iced](https://medium.com/@k8scat/building-a-modern-rust-gui-with-iced-a-comprehensive-guide-fc272704f7a5)

[jcanalesluna]

Thanks for the suggestion. I've added Iced to the GUI development tools!