[react-router-config] Add render key in route config. (#35805)

* Add render key in route config.

* Update with proper type directly from @types/react-router

* And update for nested routes.

types/react-router-config/index.d.ts

@@ -1,8 +1,9 @@
-// Type definitions for react-router-config 1.1
+// Type definitions for react-router-config 5.0
 // Project: https://github.com/ReactTraining/react-router/tree/master/packages/react-router-config, https://github.com/reacttraining/react-router
 // Definitions by: François Nguyen <https://github.com/lith-light-g>
 //                 John Reilly <https://github.com/johnnyreilly>
 //                 Phoenix He <https://github.com/NullMDR>
+//                 Mathieu TUDISCO <https://github.com/mathieutu>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.8
 
@@ -22,6 +23,7 @@ export interface RouteConfig {
     exact?: boolean;
     strict?: boolean;
     routes?: RouteConfig[];
+    render?: (props: RouteConfigComponentProps<any>) => React.ReactNode;
     [propName: string]: any;
 }