Update 'triggerEvent' examples (#663)

Update 'triggerEvent' examples

API.md

@@ -983,4 +983,4 @@ QUnit.testDone(function() {
 
 [61]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
 
-[62]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
+[62]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function

addon-test-support/@ember/test-helpers/dom/trigger-event.ts

@@ -14,16 +14,38 @@ import Target from './-target';
  * @return {Promise<void>} resolves when the application is settled
  *
  * @example
- * <caption>Using triggerEvent to Upload a file
- * When using triggerEvent to upload a file the `eventType` must be `change` and you must pass the
+ * <caption>
+ * Using `triggerEvent` to upload a file
+ *
+ * When using `triggerEvent` to upload a file the `eventType` must be `change` and you must pass the
  * `options` param as an object with a key `files` containing an array of
- * [Blob](https://developer.mozilla.org/en-US/docs/Web/API/Blob).</caption>
+ * [Blob](https://developer.mozilla.org/en-US/docs/Web/API/Blob).
+ * </caption>
  *
  * triggerEvent(
  *   'input.fileUpload',
  *   'change',
  *   { files: [new Blob(['Ember Rules!'])] }
  * );
+ *
+ *
+ * @example
+ * <caption>
+ * Using `triggerEvent` to upload a dropped file
+ *
+ * When using `triggerEvent` to handle a dropped (via drag-and-drop) file, the `eventType` must be `drop`. Assuming your `drop` event handler uses the [DataTransfer API](https://developer.mozilla.org/en-US/docs/Web/API/DataTransfer),
+ * you must pass the `options` param as an object with a key of `dataTransfer`. The `options.dataTransfer`     object should have a `files` key, containing an array of [File](https://developer.mozilla.org/en-US/docs/Web/API/File).
+ * </caption>
+ *
+ * triggerEvent(
+ *   '[data-test-drop-zone]',
+ *   'drop',
+ *   {
+ *     dataTransfer: {
+ *       files: [new File(['Ember Rules!', 'ember-rules.txt'])]
+ *     }
+ *   }
+ * )
  */
 export default function triggerEvent(
   target: Target,