docs: update Refs.mdx (#64)

Author: denisborovikov

docs/advanced/Refs.mdx

@@ -10,7 +10,7 @@ import { Input, styled } from '@smooth-ui/core-sc'
 
 Passing a `ref` prop to a Smooth UI component will give you the ref of the DOM node.
 
-> Be careful, if you use emotion or styled-components v4, you have to use "innerRef" instead of "ref".
+> Be careful, if you use emotion or styled-components v3, you have to use "innerRef" instead of "ref".
 
 <Playground>
   {() => {