Update React-Redux typedef info for 7.2.3

Author: markerikson

docs/tutorials/typescript.md

@@ -27,6 +27,12 @@ Welcome to the Redux Toolkit TypeScript Quick Start tutorial! **This tutorial wi
 
 This page focuses on just how to set up the TypeScript aspects . For explanations of what Redux is, how it works, and full examples of how to use Redux Toolkit, [see the tutorials linked in the "Tutorials Overview" page](./overview.md).
 
+Redux Toolkit is already written in TypeScript, so its TS type definitions are built in.
+
+[React Redux](https://react-redux.js.org) has its type definitions in a separate [`@types/react-redux` typedefs package](https://npm.im/@types/react-redux) on NPM. In addition to typing the library functions, the types also export some helpers to make it easier to write typesafe interfaces between your Redux store and your React components.
+
+As of React Redux v7.2.3, the `react-redux` package has a dependency on `@types/react-redux`, so the type definitions will be automatically installed with the library. Otherwise, you'll need to manually install them yourself (typically `npm install @types/react-redux` ).
+
 The [Redux+TS template for Create-React-App](https://github.com/reduxjs/cra-template-redux-typescript) comes with a working example of these patterns already configured.
 
 ## Project Setup