docs(aio): update migrated content from anguar.io

aio/content/examples/template-syntax/src/app/hero-form.component.ts

@@ -0,0 +1,30 @@
+import { Component, Input, ViewChild } from '@angular/core';
+import { NgForm }                      from '@angular/forms';
+
+import { Hero } from './hero';
+
+@Component({
+  selector: 'hero-form',
+  templateUrl: './hero-form.component.html',
+  styles: [`
+    button { margin: 6px 0; }
+    #heroForm { border: 1px solid black; margin: 20px 0; padding: 8px; max-width: 350px; }
+  `]
+})
+export class HeroFormComponent {
+  @Input() hero: Hero;
+  @ViewChild('heroForm') form: NgForm;
+
+  private _submitMessage = '';
+
+  get submitMessage() {
+    if (!this.form.valid) {
+      this._submitMessage = '';
+    }
+    return this._submitMessage;
+  }
+
+  onSubmit(form: NgForm) {
+    this._submitMessage =  'Submitted. form value is ' + JSON.stringify(form.value);
+  }
+}