Add default build target for wasm example

[Gentoli]

No description provided.

[ahrnbom]

Shouldn't it be wasm32-unknown-emscripten? What's the difference?

[Gentoli]

@ahrnbom looks like wasm32-unknown-unknown is used more with wasm-bindgen/wasm-pack (https://rustwasm.github.io/wasm-bindgen/reference/rust-targets.html). From what I see online wasm32-unknown-emscripten would provide/translate machine APIs to wasm. This is not needed here.

[ahrnbom]

Now I'm even more confused. The example README only mentions building with Trunk, and nothing about wasm-pack. If wasm-pack is an alternative to Trunk, which works with Kiss3D, I think this should be mentioned in the Readme for the WASM example

[Gentoli]

@ahrnbom wasm-bindgen/wasm-pack are used to generate javascript bindings/package for scripts in html to load/call rust wasm. trunk is similar to webpack that bundles the generated javascript so it's more compact for web.

wasm-pack is not an alternative. I only mentioned that because it's from rustwasm working group.