readme: add didInvalidatePushTokenForType delegate desc in usage

Author: zxcpoiu

README.md

@@ -109,13 +109,19 @@ Make sure you enabled the folowing in `Xcode` -> `Signing & Capabilities`:
 /* Add PushKit delegate method */
 
 // --- Handle updated push credentials
-- (void)pushRegistry:(PKPushRegistry *)registry didUpdatePushCredentials:(PKPushCredentials *)credentials forType:(NSString *)type {
+- (void)pushRegistry:(PKPushRegistry *)registry didUpdatePushCredentials:(PKPushCredentials *)credentials forType:(PKPushType)type {
   // Register VoIP push token (a property of PKPushCredentials) with server
   [RNVoipPushNotificationManager didUpdatePushCredentials:credentials forType:(NSString *)type];
 }
 
+- (void)pushRegistry:(PKPushRegistry *)registry didInvalidatePushTokenForType:(PKPushType)type
+{
+  // --- The system calls this method when a previously provided push token is no longer valid for use. No action is necessary on your part to reregister the push type. Instead, use this method to notify your server not to send push notifications using the matching push token.
+}
+
+
 // --- Handle incoming pushes (for ios <= 10)
-- (void)pushRegistry:(PKPushRegistry *)registry didReceiveIncomingPushWithPayload:(PKPushPayload *)payload forType:(NSString *)type {
+- (void)pushRegistry:(PKPushRegistry *)registry didReceiveIncomingPushWithPayload:(PKPushPayload *)payload forType:(PKPushType)type {
   [RNVoipPushNotificationManager didReceiveIncomingPushWithPayload:payload forType:(NSString *)type];
 }