Maybe they changed the blog post after you read it, but they link to their github repo (https://github.com/facebook/relay https://github.com/facebook/relay) and

Maybe they changed the blog post after you read it, but they link to their github repo (https://github.com/facebook/relay https://github.com/facebook/relay) and the NPM registry (https://www.npmjs.com/package/react-relay/ https://www.npmjs.com/package/react-relay/)