Added missing rustup target add for "web locally" (#101)

* Added missing `rustup target add` for web deploy

* Added missing `rustup target add` for "web locally"

README.md

@@ -50,9 +50,10 @@ On Fedora Rawhide you need to run:
 You can compile your app to [WASM](https://en.wikipedia.org/wiki/WebAssembly) and publish it as a web page.
 
 We use [Trunk](https://trunkrs.dev/) to build for web target.
-1. Install Trunk with `cargo install --locked trunk`.
-2. Run `trunk serve` to build and serve on `http://127.0.0.1:8080`. Trunk will rebuild automatically if you edit the project.
-3. Open `http://127.0.0.1:8080/index.html#dev` in a browser. See the warning below.
+1. Install the required target with `rustup target add wasm32-unknown-unknown`.
+2. Install Trunk with `cargo install --locked trunk`.
+3. Run `trunk serve` to build and serve on `http://127.0.0.1:8080`. Trunk will rebuild automatically if you edit the project.
+4. Open `http://127.0.0.1:8080/index.html#dev` in a browser. See the warning below.
 
 > `assets/sw.js` script will try to cache our app, and loads the cached version when it cannot connect to server allowing your app to work offline (like PWA).
 > appending `#dev` to `index.html` will skip this caching, allowing us to load the latest builds during development.