$ npm install --save-dev eslint
$ npm install --save-dev eslint-plugin-github

Run initialization wizard.

$ node_modules/.bin/eslint-github-init

Set up npm run lint script.

{
  "private": true,
  "scripts": {
    "lint": "github-lint"
  }
}

The github-lint command will run eslint, flow and flow coverage checking depending on your project configuration.