Add missing closing brace in docs

Summary:
This is a minor documentation fix

fixes #11150
Closes https://github.com/facebook/react-native/pull/11253

Differential Revision: D4268276

fbshipit-source-id: 67c8f9b4c77a2c781c09376bf4fc15a61b3db490

Libraries/PushNotificationIOS/PushNotificationIOS.js

@@ -92,9 +92,9 @@ export type PushNotificationEventName = $Enum<{
  *    }
  *    // Required for the notification event. You must call the completion handler after handling the remote notification.
  *    - (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
- *                                                           fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
+ *                                                           fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
  *    {
- *       [RCTPushNotificationManager didReceiveRemoteNotification:userInfo fetchCompletionHandler:completionHandler];
+ *      [RCTPushNotificationManager didReceiveRemoteNotification:userInfo fetchCompletionHandler:completionHandler];
  *    }
  *    // Required for the registrationError event.
  *    - (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error