Greate a gatsby app without the gatsby-cli

create-gatsby-wihtouh-gatsby-cli.md

1. Create a new folder mkdir gatsby-demo && cd $_
2. create package.json npm init -y
3. add packages npm i react react-dom gatsby
4. create page directory mkdir -p src/pages/
5. create index page in src/pages/index.js:

import React from "react"

export default () => <div>Hello world!</div>

6. run npx gatsby develop