Add async data flow diagram

Author: markerikson

docs/tutorials/essentials/part-5-async-logic.md

@@ -65,6 +65,10 @@ But, what if you want to have async logic interact with the store by dispatching
 
 There are many kinds of async middleware for Redux, and each lets you write your logic using different syntax. The most common async middleware is [`redux-thunk`](https://github.com/reduxjs/redux-thunk), which lets you write plain functions that may contain async logic directly. Redux Toolkit's `configureStore` function [automatically sets up the thunk middleware by default](https://redux-toolkit.js.org/api/getDefaultMiddleware#included-default-middleware), and [we recommend using thunks as the standard approach for writing async logic with Redux](../../style-guide/style-guide.md#use-thunks-for-async-logic).
 
+Earlier, we saw [what the synchronous data flow for Redux looks like](part-1-overview-concepts.md#redux-application-data-flow). When we introduce asynchronous logic, we add an extra step where middleware can run logic like AJAX requests, then dispatch actions. That makes the async data flow look like this:
+
+![Redux async data flow diagram](/img/tutorials/essentials/ReduxAsyncDataFlowDiagram.gif)
+
 ### Thunk Functions
 
 Once the thunk middleware has been added to the Redux store, it allows you to pass _thunk functions_ directly to `store.dispatch`. A thunk function will always be called with `(dispatch, getState)` as its arguments, and you can use them inside the thunk as needed.

docs/tutorials/fundamentals/part-6-async-logic.md

@@ -155,9 +155,9 @@ Just like with a normal action, we first need to handle a user event in the appl
 
 Once that dispatched value reaches a middleware, it can make an async call, and then dispatch a real action object when the async call completes.
 
-Earlier, we saw [a diagram that represents the normal synchronous Redux data flow](./part-2-concepts-data-flow.md#redux-application-data-flow). When we add async logic to a Redux app, the data flow sequence now looks like this:
+Earlier, we saw [a diagram that represents the normal synchronous Redux data flow](./part-2-concepts-data-flow.md#redux-application-data-flow). When we add async logic to a Redux app, we add an extra step where middleware can run logic like AJAX requests, then dispatch actions. That makes the async data flow look like this:
 
-**FIXME Add async Redux data flow diagram here**
+![Redux async data flow diagram](/img/tutorials/essentials/ReduxAsyncDataFlowDiagram.gif)
 
 ## Using the Redux Thunk Middleware