Improve feature documentation

docs/APIRef.ActionsOnElement.md

@@ -244,21 +244,32 @@ jestExpect(multipleMatchedElements.elements[0].identifier).toBe('FirstElement');
 
 ### `takeScreenshot()` Android Only
 
-Take a screenshot of the native view associated with the element in question. Useful for highly-focused visual comparison tests (i.e. comparison between elements rather than a whole screen).
+Take a screenshot of the native view associated with the element in question. Useful for highly-focused visual comparison tests (i.e. comparison between elements rather than of complete screen, with visual "noise").
 
 Returns the path of a temporary file containing the resulted `.png` image.
 
 ```js
 const bitmapPath = await element(by.id('fancy-element')).takeScreenshot();
+```
+
+A typical use case of this API is like so (i.e. taking a screenshot and saving the resulted image once, then keeping it as a snapshot of the expected result):
 
+```js
 const fs = require('fs');
-const bitmapBuffer = fs.readFileSync(bitmapPath);
+const bitmapBuffer = fs.readFileSync(bitmapPath); // bitmapPath: see above
 const snapshottedBitmapBuffer = fs.readFileSync(snapshottedBitmapPath);
 if (!bitmapBuffer.equals(expectedBitmapBuffer)) {
   throw new Error('Bitmaps differ!');
 }
 ```
 
+> A more useful way of doing this is by utilizing more advanced 3rd-party image snapshotting and comparison tools such as [applitools](https://applitools.com).
+
+Caveats:
+
+* Currently, the image-file generated by Detox is stored in a temporary folder, and does not get automatically cleaned-up.
+* The image-file does not get exported as a test artifact in the test's finalization (i.e. such as with [device.takeScreenshot(name)](https://github.com/wix/Detox/blob/master/docs/APIRef.DeviceObjectAPI.md#devicetakescreenshotname)).
+
 ## Deprecated Methods
 
 - [`.tapAtPoint()`](#tapatpointpoint)