Getting started does not work for AssemblyScript
When following the Getting started tutorial I spotted several problems:

1. Installing w4 as global is not the best solution as it may differ for projects and it is problematic to update. Better to be installed locally and executed via `npx`. See https://www.assemblyscript.org/quick-start.html for inspiration.
2. Initialization doesn't work - The result from Setup instructions is `Cannot GET /` for http://localhost:4444/
3. There are library files in `src` - wasm4.ts is a library source, I would expect it to be referenced in package.json as a devDependencies, not in the src directory as it is not supposed to be edited by the user.
