Match official TS docs style for clarity

Closes #4463

Author: timdorr

docs/usage/UsageWithTypescript.md

@@ -87,7 +87,8 @@ import type { RootState, AppDispatch } from './store'
 
 // highlight-start
 // Use throughout your app instead of plain `useDispatch` and `useSelector`
-export const useAppDispatch: () => AppDispatch = useDispatch
+type DispatchFunc = () => AppDispatch
+export const useAppDispatch: DispatchFunc = useDispatch
 export const useAppSelector: TypedUseSelectorHook<RootState> = useSelector
 // highlight-end
 ```