Fill out "About Yoga", "Laying out a Yoga tree" , and "Styling" (#1591)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1591

Adds initial documentation to these sections.

Reviewed By: joevilches

Differential Revision: D54708141

fbshipit-source-id: b2c1ac20573840833a3e5fde8c7b53f2770cecbd

website-next/docs/styling/flex-wrap.mdx

@@ -0,0 +1,33 @@
+---
+sidebar_position: 7
+---
+
+import Playground from '@site/src/components/Playground';
+
+# Flex Wrap
+
+The `flex wrap` property is set on containers and controls what happens when
+children overflow the size of the container along the main axis. By default
+children are forced into a single line (which can shrink nodes). When wrapping lines [`align content`](/docs/styling/align-content) can be used to specify how the
+lines are placed in the container.
+
+**No wrap (default)**: No wrapping and children might shrink as a result.
+
+**Wrap**: Nodes are wrapped into multiple lines along the main axis if needed.
+
+**Wrap reverse**: Behaves the same as `wrap` but the order of the lines is reversed.
+
+<Playground code={`<Layout config={{useWebDefaults: false}}>
+  <Node
+    style={{
+      width: 250,
+      height: 250,
+      padding: 10,
+      flexWrap: 'wrap'
+    }}>
+    <Node style={{margin: 5, height: 50, width: 50}} />
+    <Node style={{margin: 5, height: 50, width: 50}} />
+    <Node style={{margin: 5, height: 50, width: 50}} />
+    <Node style={{margin: 5, height: 50, width: 50}} />
+  </Node>
+</Layout>`} />