Website readme

Summary: Updating readme

Reviewed By: emilsjolander

Differential Revision: D6975778

fbshipit-source-id: c27a074c8d512e72de63ffa1d2f06f18a4f8e2c5

website/README.md

@@ -1,6 +1,35 @@
 # Yoga documentation and playground
 
-This uses [gatsby.js](https://www.gatsbyjs.org/).
+This site uses [gatsby.js](https://www.gatsbyjs.org/) as static site generator. Which transforms all markdown and react code to static HTML and JS files.
 
-- Run `yarn develop` during development
+## Development
-- Run `yarn build` to generate site
+```
+yarn install
+yarn develop
+```
+
+### Structure
+Documentation pages are generated from the Markdown files in `contents/`. The files are organized in 4 sections/folders (getting-started, properties, examples, contributing) which are dynamically listed on the docs overview page. The Markdown files can have some header files containing metadata.
+
+```
+---
+path: "docs/flexDirection"
+title: "Flex Direction"
+hasPlayground: true
+editableProperties: ['flexDirection']
+---
+```
+
+The `path` can be any URL this page should be available at. The `title` is used as the page's HTML-title and when referencing the file from the documentation overview. There are two kinds of templates for a page: with and without playground. `hasPlayground` selects the corresponding template (`src/templates/{with|without}Playground.js`). When using `hasPlayground: true`, `editableProperties` can list all Yoga properties which are editable in the playground.
+
+### Design
+We are using [antd](https://ant.design) for various UI elements. See their documentation for the components available. `gatsby-config.js` can be used to overwrite LESS-variables from antd.
+
+For styling react components we create a CSS-file with the same name next to each component and import it in the component. E.g. there is `index.js` and `index.css`. In the react-component we import the stylesheet: `import './index.css'`.
+
+## Build
+To generate the static files run:
+```
+yarn build
+```
+The output will be in `public/` and can be published on GitHub pages.