docs(ngModelOptions): mention that it's inherited

src/ng/directive/input.js

@@ -2803,6 +2803,8 @@ var ngValueDirective = function() {
  * `submit` event. Note that `ngClick` events will occur before the model is updated. Use `ngSubmit`
  * to have access to the updated model.
  *
+ * `ngModelOptions` has an effect on the element it's declared on and its descendants.
+ *
  * @param {Object} ngModelOptions options to apply to the current model. Valid keys are:
  *   - `updateOn`: string specifying which event should be the input bound to. You can set several
  *     events using an space delimited list. There is a special event called `default` that