Update Readme to cover need for Manifest.permission.POST_NOTIFICATIONS for targetSdk = 33

[MKevin3]

If you target SDK 33 you must request Manifest.permission.POST_NOTIFICATIONS or you will not see the notification as network traffic occurs. This is not required for older SDK version. You can do this only for debug builds if you don't need notification support otherwise in your app.

Please update the configuration steps in the readme.md to give users a heads up about this new requirement.