Fix controlled state example

content/blog/2018-05-23-react-v-16-4.md

@@ -52,8 +52,8 @@ static getDerivedStateFromProps(props, state) {
   const prevProps = state.prevProps;
   // Compare incoming props to previous props
   const controlledValue =
-    prevProps.value !== state.controlledValue
-      ? prevProps.value
+    prevProps.value !== props.value
+      ? props.value
       : state.controlledValue;
   return {
     // Store the previous props in state