Remove exact from React Router routes

[mattbal]

What docs page needs to be fixed?

https://redux.js.org/tutorials/essentials/part-6-performance-normalization#adding-user-pages

What is the problem?

React Router v6 no longer supports exact for routes. From the docs:

<Route exact> is gone. Instead, routes with descendant routes (defined in other components) use a trailing * in their path to indicate they match deeply

What should be changed to fix the problem?

Remove exact from the App.tsx code block