docs(form): remove mention of interpolated control names not being supported

The docs state that interpolation cannot be used in control names.
This used to be true, but not anymore.

Closes angular#13520

Author: gkalpak

src/ng/directive/form.js

@@ -337,13 +337,9 @@ function FormController(element, attrs, $scope, $animate, $interpolate) {
  *
  * In Angular, forms can be nested. This means that the outer form is valid when all of the child
  * forms are valid as well. However, browsers do not allow nesting of `<form>` elements, so
- * Angular provides the {@link ng.directive:ngForm `ngForm`} directive which behaves identically to
- * `<form>` but can be nested.  This allows you to have nested forms, which is very useful when
- * using Angular validation directives in forms that are dynamically generated using the
- * {@link ng.directive:ngRepeat `ngRepeat`} directive. Since you cannot dynamically generate the `name`
- * attribute of input elements using interpolation, you have to wrap each set of repeated inputs in an
- * `ngForm` directive and nest these in an outer `form` element.
- *
+ * Angular provides the {@link ng.directive:ngForm `ngForm`} directive, which behaves identically to
+ * `form` but can be nested. Nested forms can be useful, for example, if the validity of a sub-group
+ * of controls needs to be determined.
  *
  * # CSS classes
  *  - `ng-valid` is set if the form is valid.