message: Add usage section to `iced_web`
diff: @@ -25,3 +25,41 @@ __Iced moves fast and the `master` branch can contain breaking changes!__ If
  you want to learn about a specific release, check out [the release list].
  [the release list]: https://github.com/hecrj/iced/releases
  +
  +## Usage
  +The current build process is a bit involved, as [`wasm-pack`] does not currently [support building binary crates](https://github.com/rustwasm/wasm-pack/issues/734).
  +
  +Therefore, we instead build using the `wasm32-unknown-unknown` target and use the [`wasm-bindgen`] CLI to generate appropriate bindings.
  +
  +For instance, let's say we want to build the [`tour` example]:
  +
  +```
  +cd examples
  +cargo build --example tour --target wasm32-unknown-unknown
  +wasm-bindgen ../target/wasm32-unknown-unknown/debug/examples/tour.wasm --out-dir tour --web
  +```
  +
  +Then, we need to create an `.html` file to load our application:
  +
  +```html
  +<!DOCTYPE html>
  +<html>
  + <head>
  + <meta http-equiv="Content-type" content="text/html; charset=utf-8"/>
  + <title>Tour - Iced</title>
  + </head>
  + <body>
  + <script type="module">
  + import init from "./tour/tour.js";
  +
  + init('./tour/tour_bg.wasm');
  + </script>
  + </body>
  +</html>
  +```
  +
  +Finally, we serve it using an HTTP server and access it with our browser.
  +
  +[`wasm-pack`]: https://github.com/rustwasm/wasm-pack
  +[`wasm-bindgen`]: https://github.com/rustwasm/wasm-bindgen
  +[`tour` example]: ../examples/README.md#tour
  