Add twiml() to readme

Author: TechWilk

README.md

@@ -131,7 +131,7 @@ class AccountApproved extends Notification
 }
 ```
 
-Or create a Twilio call:
+Or create a Twilio call, using either an external TwiML url:
 
 ``` php
 use NotificationChannels\Twilio\TwilioChannel;
@@ -153,6 +153,32 @@ class AccountApproved extends Notification
 }
 ```
 
+Or create a Twilio call, and send a TwiML response directly:
+
+``` php
+use NotificationChannels\Twilio\TwilioChannel;
+use NotificationChannels\Twilio\TwilioCallMessage;
+use Illuminate\Notifications\Notification;
+use Twilio\TwiML\VoiceResponse;
+
+class AccountApproved extends Notification
+{
+    public function via($notifiable)
+    {
+        return [TwilioChannel::class];
+    }
+
+    public function toTwilio($notifiable)
+    {
+        return (new TwilioCallMessage())
+            ->twiml(
+                (new VoiceResponse())
+                    ->say('Hello world')
+            );
+    }
+}
+```
+
 In order to let your Notification know which phone are you sending/calling to, the channel will look for the `phone_number` attribute of the Notifiable model. If you want to override this behaviour, add the `routeNotificationForTwilio` method to your Notifiable model.
 
 ```php
@@ -174,6 +200,9 @@ public function routeNotificationForTwilio()
 
 - `from('')`: Accepts a phone to use as the notification sender.
 - `url('')`: Accepts an url for the call TwiML.
+- `twiml(VoiceResponse)`: Accepts a \Twilio\TwiML\VoiceResponse containing the call TwiML.
+
+> You can use *either* url() *or* twiml() on a TwilioCallMessage object, not both.
 
 ## Changelog