add wasm32 readme note

README.md

@@ -9,7 +9,11 @@ This is a simple [Rust](https://www.rust-lang.org/) Web [Axum](https://docs.rs/a
 #### Rustup
 First install Rust. I suggest using the [rustup toolchain](https://rustup.rs/)
 
-Then run `cargo install trunk`
+Then run 
+```bash
+cargo install trunk
+rustup target install wasm32-unknown-unknown
+```
 
 Finally, run both the backend and frontend to use the application