Update README.md

Co-authored-by: Christian Lück <[email protected]>

Author: 51imyyy

README.md

@@ -2407,12 +2407,7 @@ the [`withHeader()` method](#withheader).
 ```php
 $browser = $browser->withoutHeader('User-Agent');
 
-$browser->get($url)->then(function (Psr\Http\Message\ResponseInterface $response) {
-    //won't contain the User-Agent header
-    var_dump($response);
-}, function (Exception $e) {
-    echo 'Error: ' . $e->getMessage() . PHP_EOL;
-});
+$browser->get($url)->then(…);
 ```
 
 Note that this method only affects the headers which were set with the