docs: several minor NgModule guide fixes/improvements (#21589)

PR Close #21589

aio/content/examples/lazy-loading-ngmodules/src/app/customers/customers-routing.module.ts

@@ -15,8 +15,7 @@ const routes: Routes = [
 
 @NgModule({
   imports: [RouterModule.forChild(routes)],
-  exports: [RouterModule],
-  providers: []
+  exports: [RouterModule]
 })
 export class CustomersRoutingModule { }
 // #enddocregion customers-routing-module

aio/content/examples/lazy-loading-ngmodules/src/app/orders/orders-routing.module.ts

@@ -6,23 +6,17 @@ import { Routes, RouterModule } from '@angular/router';
 // #docregion orders-routing-module-detail
 import { OrderListComponent } from './order-list/order-list.component';
 
-
 const routes: Routes = [
   {
     path: '',
     component: OrderListComponent
   }
 ];
-
 // #enddocregion orders-routing-module-detail
 
 @NgModule({
-  imports: [
-    RouterModule.forChild(routes)
-  ],
-  exports: [
-    RouterModule
-  ]
+  imports: [RouterModule.forChild(routes)],
+  exports: [RouterModule]
 })
 export class OrdersRoutingModule { }
 // #enddocregion orders-routing-module