Added React.forwardRef to API and docs

examples/forwarding-refs/fancy-button-ref.js

@@ -0,0 +1,15 @@
+import FancyButton from './FancyButton';
+
+// highlight-next-line
+const ref = React.createRef();
+
+// The FancyButton component we imported is the LogProps HOC.
+// Even though the rendered output will be the same,
+// Our ref will point to LogProps instead of the inner FancyButton component!
+// This means we can't call e.g. ref.current.focus()
+// highlight-range{4}
+<FancyButton
+  label="Click Me"
+  handleClick={handleClick}
+  ref={ref}
+/>;