docs(forms): migrate @whatItDoes tags to the description (#23186)

We get the overview for the doc by splitting off the first
paragraph.

PR Close #23186

packages/forms/src/directives/ng_model.ts

@@ -46,7 +46,9 @@ export const formControlBinding: any = {
 const resolvedPromise = Promise.resolve(null);
 
 /**
- * @whatItDoes Creates a {@link FormControl} instance from a domain model and binds it
+ * @description
+ *
+ * Creates a {@link FormControl} instance from a domain model and binds it
  * to a form control element.
  *
  * The {@link FormControl} instance will track the value, user interaction, and
@@ -54,8 +56,6 @@ const resolvedPromise = Promise.resolve(null);
  * within a parent form, the directive will also register itself with the form as a child
  * control.
  *
- * @description
- *
  * This directive can be used by itself or as part of a larger form. All you need is the
  * `ngModel` selector to activate it.
  *