feat(doc): move module to standalone

apps/angular/module-to-standalone/src/app/app.module.ts

@@ -0,0 +1,11 @@
+import { MainShellModule } from '@angular-challenges/module-to-standalone/shell';
+import { NgModule } from '@angular/core';
+import { BrowserModule } from '@angular/platform-browser';
+import { AppComponent } from './app.component';
+
+@NgModule({
+  declarations: [AppComponent],
+  imports: [BrowserModule, MainShellModule],
+  bootstrap: [AppComponent],
+})
+export class AppModule {}