Remove mention of deprecated ReactLink add-on (#6535)

docs/thinking-in-react.md

@@ -134,7 +134,7 @@ You can start seeing how your application will behave: set `filterText` to `"bal
 
 So far, we've built an app that renders correctly as a function of props and state flowing down the hierarchy. Now it's time to support data flowing the other way: the form components deep in the hierarchy need to update the state in `FilterableProductTable`.
 
-React makes this data flow explicit to make it easy to understand how your program works, but it does require a little more typing than traditional two-way data binding. React provides an add-on called `ReactLink` to make this pattern as convenient as two-way binding, but for the purpose of this post, we'll keep everything explicit.
+React makes this data flow explicit to make it easy to understand how your program works, but it does require a little more typing than traditional two-way data binding.
 
 If you try to type or check the box in the current version of the example, you'll see that React ignores your input. This is intentional, as we've set the `value` prop of the `input` to always be equal to the `state` passed in from `FilterableProductTable`.