docs(aio): updated i18n guide and example (#19975)

aio/content/examples/i18n/doc-files/main.2.ts

@@ -0,0 +1,22 @@
+// #docregion
+import { enableProdMode, TRANSLATIONS, TRANSLATIONS_FORMAT } from '@angular/core';
+import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
+
+import { AppModule } from './app/app.module';
+import { environment } from './environments/environment';
+
+if (environment.production) {
+  enableProdMode();
+}
+
+// use the require method provided by webpack
+declare const require;
+// we use the webpack raw-loader to return the content as a string
+const translations = require(`raw-loader!./locale/messages.fr.xlf`);
+
+platformBrowserDynamic().bootstrapModule(AppModule, {
+  providers: [
+    {provide: TRANSLATIONS, useValue: translations},
+    {provide: TRANSLATIONS_FORMAT, useValue: 'xlf'}
+  ]
+});