docs(react-native): remove references to iOS firebase usage

packages/react-native-sdk/docusaurus/docs/reactnative/06-advanced/04-push-notifications/03-ringing-setup/01-react-native.mdx

@@ -144,7 +144,6 @@ At the top of the file, right after '#import "AppDelegate.h"', add the following
 
 ```objectivec
 // highlight-start
-#import <Firebase.h>
 #import "RNCallKeep.h"
 #import <PushKit/PushKit.h>
 #import "RNVoipPushNotificationManager.h"
@@ -158,9 +157,6 @@ We need to configure the Firebase library, set up the callkeep library and regis
 ```objectivec
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
-  // highlight-next-line
-  [FIRApp configure];
-
   // highlight-start
   NSString *localizedAppName = [[[NSBundle mainBundle] localizedInfoDictionary] objectForKey:@"CFBundleDisplayName"];
   NSString *appName = [[[NSBundle mainBundle] infoDictionary]objectForKey :@"CFBundleDisplayName"];
@@ -363,4 +359,4 @@ StreamVideoRN.onPushLogout();
 
 - During development, you may be facing a situation where push notification is shown but its events like accepting or rejecting a call don't work. This is because, during hot module reloading the global event listeners may get de-registered. To properly test during development, make sure that you fully restart the app or test in release mode without the metro packager.
 - You can check the "Webhook & Push Logs" section in the [Stream Dashboard](https://dashboard.getstream.io/) to see if Notifications were sent by Stream.
-- If you are still having trouble with Push Notifications, please submit a ticket to us at [support](https://getstream.io/contact/support/).
+- If you are still having trouble with Push Notifications, please submit a ticket to us at [support](https://getstream.io/contact/support/).