Add example SparkPost API options

Author: Lidbetter

README.md

@@ -30,14 +30,19 @@ Or by setting the environment variable `MAIL_DRIVER` in your .env file
 MAIL_DRIVER=sparkpost
 ```
 
-If you need to pass any options to the guzzle client instance which is making the request to the sparkpost API, you can do so by setting the 'guzzle' options in `config/services.php`
+If you need to pass any options to the guzzle client instance which is making the request to the sparkpost API, you can do so by setting the 'guzzle' options in `config/services.php`. Also you can provide options to pass to the SparkPost API by setting the 'options' array.
 ```php
 'sparkpost' => [
     'secret' => env('SPARKPOST_SECRET'),
     'guzzle' => [
         'verify' => true,
         'decode_content' => true,
-    ]
+    ],
+    'options' => [
+        'open_tracking' => false,
+        'click_tracking' => false,
+        'transactional' => true,
+    ],
 ],
 ```