docs: add button type in form array example (#43666)

add a button type in the example of creating a dynamic form so that the button that adds the alias control does not submit the entire form

PR Close #43666

aio/content/examples/reactive-forms/src/app/profile-editor/profile-editor.component.html

@@ -27,7 +27,7 @@
   <!-- #docregion formarrayname -->
   <div formArrayName="aliases">
     <h2>Aliases</h2>
-    <button (click)="addAlias()">+ Add another alias</button>
+    <button (click)="addAlias()" type="button">+ Add another alias</button>
 
     <div *ngFor="let alias of aliases.controls; let i=index">
       <!-- The repeated alias template -->