Migrate website to Docusaurus 2

Summary:
Docusaurus 2 is quite a lot more powerful than docu 1 it turns out.
This should convert the website fully.

* [done] Go through migration guide https://v2.docusaurus.io/docs/migrating-from-v1-to-v2
* [done] Convert landing page html
* [done] Convert all images to img tags
* [done] Convert all .md files to .mdx
* [done] Make sure ui-doc generation and including still works
* [done] Scan every page visually for sanity check
* [done] Make sure footer still works
* [done] Make sure search still works
* [done] Change all links/ to links/index
* [done] Change all links.md to links
* [done] Add some custom css to make the navbar look like the old one and darken the footer.

Reviewed By: passy

Differential Revision: D21158717

fbshipit-source-id: 5f45b711b1b6fd5ece4c5c15c55635c7ebbfb568

website/docusaurus.config.js

@@ -0,0 +1,101 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+const repoUrl = 'https://github.com/facebook/flipper';
+
+const siteConfig = {
+  title: 'Flipper',
+  tagline: 'Extensible mobile app debugging',
+  url: 'https://fbflipper.com/',
+  baseUrl: '/',
+  projectName: 'flipper',
+  themeConfig: {
+    navbar: {
+      title: 'Flipper',
+      logo: {
+        alt: 'Flipper Logo',
+        src: 'img/icon.png',
+      },
+      links: [
+        {to: 'docs/features/index', label: 'Features', position: 'right'},
+        {to: 'docs/getting-started/index', label: 'Setup', position: 'right'},
+        {to: 'docs/extending/index', label: 'Extending', position: 'right'},
+        {href: repoUrl, label: 'GitHub', position: 'right'},
+      ],
+    },
+    disableDarkMode: true,
+    footer: {
+      style: 'dark',
+      links: [
+        {
+          title: 'Learn',
+          items: [
+            {label: 'Getting Started', to: 'docs/getting-started/index'},
+            {label: 'Plugin Creation Tutorial', to: 'docs/tutorial/intro'},
+          ],
+        },
+        {
+          title: 'Plugins',
+          items: [
+            {label: 'Core Plugins', to: 'docs/features'},
+            {
+              label: 'Community Plugins',
+              to: 'https://www.npmjs.com/search?q=keywords:flipper-plugin',
+            },
+          ],
+        },
+        {
+          title: 'More',
+          items: [
+            {label: 'Twitter', to: 'https://twitter.com/flipper_fb'},
+            {label: 'GitHub', to: repoUrl},
+          ],
+        },
+      ],
+      copyright: 'Copyright © ' + new Date().getFullYear() + ' Facebook',
+      logo: {
+        alt: 'Flipper Mascot',
+        src: 'img/mascot.png',
+        title: "I'm a dolphin not a whale!",
+      },
+    },
+    algolia: {
+      apiKey: '2df980e7ffc95c19552790f7cad32666',
+      indexName: 'fbflipper',
+      algoliaOptions: {
+        hitsPerPage: 5,
+      },
+    },
+  },
+  favicon: 'img/icon.png',
+  scripts: [
+    'https://buttons.github.io/buttons.js',
+    'https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.0/clipboard.min.js',
+    '/js/code-blocks-buttons.js',
+    '/js/google-analytics.js',
+  ],
+  stylesheets: [],
+  presets: [
+    [
+      '@docusaurus/preset-classic',
+      {
+        docs: {
+          path: '../docs',
+          sidebarPath: require.resolve('./sidebars.json'),
+          editUrl: 'https://github.com/facebook/flipper/blob/master/website',
+        },
+        theme: {
+          customCss: require.resolve('./static/css/custom.css'),
+        },
+      },
+    ],
+  ],
+};
+
+module.exports = siteConfig;