fix doc comments

Author: lohanidamodar

templates/flutter/lib/src/client_stub.dart.twig

@@ -1,6 +1,6 @@
 import 'client_base.dart';
 
-/// Implemented in `browser_client.dart` and `io_client.dart`.
+/// Implemented in `client_browser.dart` and `client_io.dart`.
 ClientBase createClient({required String endPoint, required bool selfSigned}) =>
     throw UnsupportedError(
         'Cannot create a client without dart:html or dart:io.');

templates/flutter/lib/src/realtime_stub.dart.twig

@@ -1,6 +1,6 @@
 import 'realtime_base.dart';
 import 'client.dart';
 
-/// Implemented in `browser_client.dart` and `io_client.dart`.
+/// Implemented in `realtime_browser.dart` and `realtime_io.dart`.
 RealtimeBase createRealtime(Client client) => throw UnsupportedError(
     'Cannot create a client without dart:html or dart:io.');