Document how to test for cancelation (#376)

readme.md

@@ -280,7 +280,21 @@ When given an unsupported protocol.
 
 ## Aborting the request
 
-The promise returned by Got has a `.cancel()` function which, when called, aborts the request.
+The promise returned by Got has a [`.cancel()`](https://github.com/sindresorhus/p-cancelable) method which, when called, aborts the request.
+
+```js
+const request = got(url, options);
+
+request.catch(err => {
+  if (request.canceled) {
+    // Handle cancelation
+  }
+  
+  // Handle other errors
+});
+
+request.cancel();
+```
 
 
 ## Proxies