Add quickstart that uses prebuilt components

This book aims to make it easier to get started working with Wasm components. The initial quickstart should not require a user to download language specific tooling. Instead, once the Bytecode Alliance registry is stood up, we should have a quickstart that uses prebuilt components that are hosted in a registry. We can walk through using `wasm-tools component wit` to see the world each component exposes and use `wac plug` to compose.