docs: add missing comma in RN setup (#1077)

In case other people are lazy and copy from the docs and get confused
about why their build fails 🤦

packages/react-native-sdk/docusaurus/docs/reactnative/06-advanced/04-push-notifications/02-setup.mdx

@@ -118,7 +118,7 @@ We need to configure the Firebase library, set up the callkeep library and regis
   // add your app name here
   // highlight-start
   [RNCallKeep setup:@{
-    @"appName": @"My awesome app"
+    @"appName": @"My awesome app",
     @"supportsVideo": @YES,
     // pass @YES here if you want the call to be shown in calls history in the built-in dialer app
     @"includesCallsInRecents": @NO,