move docs for default-router-state-serializer to configuration.md

projects/ngrx.io/content/guide/router-store/configuration.md

@@ -10,10 +10,14 @@ interface StoreRouterConfig {
 </code-example>
 
 - `stateKey`: The name of reducer key, defaults to `router`. It's also possible to provide a selector function.
-- `serializer`: How a router snapshot is serialized. Defaults to `DefaultRouterStateSerializer` (see [Default Router State Serializer](guide/router-store/default-router-state-serializer)). See [Custom Router State Serializer](#custom-router-state-serializer) for more information.
+- `serializer`: How a router snapshot is serialized. Defaults to `DefaultRouterStateSerializer` (see [Default Router State Serializer](#default-router-state-serializer)). See [Custom Router State Serializer](#custom-router-state-serializer) for more information.
 - `navigationActionTiming`: When the `ROUTER_NAVIGATION` is dispatched. Defaults to `NavigationActionTiming.PreActivation`. See [Navigation Action Timing](#navigation-action-timing) for more information.
 - `routerState`: Set this property to decide which serializer should be used, if none is provided, and the metadata on the dispatched action.
 
+## Default Router State Serializer
+
+If no router state serializer is provided through the [configuration](#configuration-options) of router store, the `DefaultRouterStateSerializer` is used. This router state serializer, serializes the URL together with the [ActivatedRouteSnapshot](https://angular.io/api/router/ActivatedRouteSnapshot) from [Angular Router](https://angular.io/guide/router). The latter is serialized recursively, but only with the possibility to traverse the route downward since `root` and `parent` parameters are set to `undefined`.
+
 ## Custom Router State Serializer
 
 During each navigation cycle, a `RouterNavigationAction` is dispatched with a snapshot of the state in its payload, the `RouterStateSnapshot`. The `RouterStateSnapshot` is a large complex structure, containing many pieces of information about the current state and what's rendered by the router. This can cause performance

projects/ngrx.io/content/navigation.json

@@ -199,10 +199,6 @@
         {
           "title": "Configuration",
           "url": "guide/router-store/configuration"
-        },
-        {
-          "title": "Default Router State Serializer",
-          "url": "guide/router-store/default-router-state-serializer"
         }
       ]
     },