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/deploy-your-site.md

@@ -0,0 +1,31 @@
+---
+sidebar_position: 5
+---
+
+# Deploy your site
+
+Docusaurus is a **static-site-generator** (also called **[Jamstack](https://jamstack.org/)**).
+
+It builds your site as simple **static HTML, JavaScript and CSS files**.
+
+## Build your site
+
+Build your site **for production**:
+
+```bash
+npm run build
+```
+
+The static files are generated in the `build` folder.
+
+## Deploy your site
+
+Test your production build locally:
+
+```bash
+npm run serve
+```
+
+The `build` folder is now served at [http://localhost:3000/](http://localhost:3000/).
+
+You can now deploy the `build` folder **almost anywhere** easily, **for free** or very small cost (read the **[Deployment Guide](https://docusaurus.io/docs/deployment)**).