Docusarus: Init Project

Summary:
This starts us transitioning the Yoga website off of an ancient version of Gatsby by initializing a new Docusaurus project. This commit adds a new stock project, to be filled in later, then fixes license lint errors.

Note that this seems to have init'd using npm, but in the next diff I convert this to yarn workspaces anyway.

Differential Revision: D46884434

fbshipit-source-id: 26e2ecba057ae99c4ef878e4cd21c8d21a25c2b5

website-next/.docusaurus/docusaurus-plugin-content-docs/default/site-docs-intro-md-0e3.json

@@ -0,0 +1,23 @@
+{
+  "unversionedId": "intro",
+  "id": "intro",
+  "title": "Tutorial Intro",
+  "description": "Let's discover Docusaurus in less than 5 minutes.",
+  "source": "@site/docs/intro.md",
+  "sourceDirName": ".",
+  "slug": "/intro",
+  "permalink": "/docs/intro",
+  "draft": false,
+  "editUrl": "https://github.com/facebook/yoga/tree/main/website/docs/intro.md",
+  "tags": [],
+  "version": "current",
+  "sidebarPosition": 1,
+  "frontMatter": {
+    "sidebar_position": 1
+  },
+  "sidebar": "tutorialSidebar",
+  "next": {
+    "title": "Tutorial - Basics",
+    "permalink": "/docs/category/tutorial---basics"
+  }
+}