[go_router] Fix some broken links in doc (flutter#3288)

[go_router] Fix some broken links in doc

Author: dddrop

packages/go_router/doc/configuration.md

@@ -31,7 +31,7 @@ GoRoute(
 To navigate to this route, use
 [go()](https://pub.dev/documentation/go_router/latest/go_router/GoRouter/go.html).
 To learn more about how navigation, visit the
-[Navigation](https://pub.dev/documentation/go_router/topics/Configuration-topic.html)
+[Navigation](https://pub.dev/documentation/go_router/latest/topics/Navigation-topic.html)
 topic.
 
 # Parameters
@@ -90,9 +90,7 @@ Some apps display destinations in a subsection of the screen, for example, an
 app using a BottomNavigationBar that stays on-screen when navigating between
 destinations.
 
-To add an additional Navigator, use
-[ShellRoute](https://pub.dev/documentation/go_router/ShellRoute-class.html)
-and provide a builder that returns a widget:
+To add an additional Navigator, use [ShellRoute][] and provide a builder that returns a widget:
 
 ```dart
 ShellRoute(
@@ -152,4 +150,5 @@ final _router = GoRouter(
 
 [GoRouter]: https://pub.dev/documentation/go_router/latest/go_router/GoRouter-class.html
 [GoRoute]: https://pub.dev/documentation/go_router/latest/go_router/GoRoute-class.html
-[GoRouterState]: https://pub.dev/documentation/go_router/latest/go_router/GoRouterState-class.html
+[GoRouterState]: https://pub.dev/documentation/go_router/latest/go_router/GoRouterState-class.html
+[ShellRoute]: https://pub.dev/documentation/go_router/latest/go_router/ShellRoute-class.html