Docusarus: Init Project (#1312)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1312

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.

Reviewed By: yungsters

Differential Revision: D46884434

fbshipit-source-id: 7a0a4dddc144ad2d22cd18a02e8dcb9ff2184489

website-next/docs/tutorial-basics/congratulations.md

@@ -0,0 +1,23 @@
+---
+sidebar_position: 6
+---
+
+# Congratulations!
+
+You have just learned the **basics of Docusaurus** and made some changes to the **initial template**.
+
+Docusaurus has **much more to offer**!
+
+Have **5 more minutes**? Take a look at **[versioning](../tutorial-extras/manage-docs-versions.md)** and **[i18n](../tutorial-extras/translate-your-site.md)**.
+
+Anything **unclear** or **buggy** in this tutorial? [Please report it!](https://github.com/facebook/docusaurus/discussions/4610)
+
+## What's next?
+
+- Read the [official documentation](https://docusaurus.io/)
+- Modify your site configuration with [`docusaurus.config.js`](https://docusaurus.io/docs/api/docusaurus-config)
+- Add navbar and footer items with [`themeConfig`](https://docusaurus.io/docs/api/themes/configuration)
+- Add a custom [Design and Layout](https://docusaurus.io/docs/styling-layout)
+- Add a [search bar](https://docusaurus.io/docs/search)
+- Find inspirations in the [Docusaurus showcase](https://docusaurus.io/showcase)
+- Get involved in the [Docusaurus Community](https://docusaurus.io/community/support)