docs: add customizing route behavior guide for router (angular#63398)

PR Close angular#63398

Author: bencodezen

adev/src/app/sub-navigation-data.ts

@@ -395,6 +395,12 @@ const DOCS_SUB_NAVIGATION_DATA: NavigationItem[] = [
             contentPath: 'guide/routing/rendering-strategies',
             status: 'new',
           },
+          {
+            label: 'Customizing route behavior',
+            path: 'guide/routing/customizing-route-behavior',
+            contentPath: 'guide/routing/customizing-route-behavior',
+            status: 'new',
+          },
           {
             label: 'Router reference',
             path: 'guide/routing/router-reference',