make npm module

Summary: We want to use the yoga playground as a standalone package as well. This adds a webpack config to bundle the playground for npm. The package can then be distributed as `yoga-playground` via npm

Reviewed By: fabiomassimo

Differential Revision: D16583334

fbshipit-source-id: 84807ddd8983ba9f0fb43570b518c975f35544ab

website/src/pages/index.js

@@ -12,7 +12,7 @@ import {Button} from 'antd';
 import React from 'react';
 import Page from '../components/Page';
 import Padded from '../components/Padded';
-import Playground from '../components/Playground';
+import Playground from '../components/Playground/src';
 import {Row, Col} from 'antd';
 import './index.css';
 import ReactNativeLogo from './logos/reactnative.png';
@@ -144,10 +144,7 @@ const AboutSectionOne = () => (
         <img src={ReactNativeLogo} />
         <h3>React Native</h3>
       </a>
-      <a
-        href="https://react-pdf.org/"
-        target="_blank"
-        className="logo">
+      <a href="https://react-pdf.org/" target="_blank" className="logo">
         <img src={ReactPDFLogo} />
         <h3>React-PDF</h3>
       </a>