Update wasm-bindgen / wasm-pack description

[jstarry]

In https://yew.rs/docs/getting-started/project-setup is written: We don't recommend using wasm-bindgen directly because it requires hand-writing some JavaScript to bootstrap you WebAssembly binary.

But wasm-pack and wasm-bindgen both can use same /examples/static/index.html file. No other steps are needed. Neither of them needs to use bundler when compiled with --target web

Context: yewstack/yew#1165 (comment)

cc @fbucek