Add question to the FAQ

docs/api/image-tracker.md

 **Example**
 
 ```js
-const imageTracker = AR.Tracker.Image({
+const tracker = AR.Tracker.Image({
     resolution: "sm"
 });
 ```

docs/faq.md

 
 Yes. You can increase the [resolution of the tracker](api/image-tracker.md#instantiation), as well as the [resolution of the camera](api/camera-source.md#instantiation), using the API. You can also increase the resolution of the rendered virtual scene by setting the [resolution of the viewport](api/viewport.md#instantiation). Performance is affected by various factors such as upload times (GPU). Test your AR experience on your target devices to find a good balance between performance and increased resolution.
 
+## How do I know which image is detected?
+
+Add an [event listener](api/image-tracker.md#targetfound) to the Image Tracker, as in the example:
+
+```js
+const tracker = AR.Tracker.Image();
+
+// ...
+
+tracker.addEventListener('targetfound', event => {
+
+    // print the name of the Reference Image
+    console.log('Found target: ' + event.referenceImage.name);
+
+});
+```
+
 ## Any recommendations?
 
 Refer to the [recommendations](./recommendations.md).