Update README.md

Author: jmrieger

README.md

@@ -1,5 +1,8 @@
 #  OneSignal Push Notifications for Laravel 5
 
+# WARNING!
+This project is not actively maintained as of 2018/12/12. I'd strongly urge you to consider a package that is, like `berkayk/onesignal-laravel`
+
 ## Introduction
 
 This project is a wrapper for the OneSignal v1 API.  It supports all operations currently supported by the API.
@@ -109,4 +112,4 @@ https://documentation.onesignal.com/docs/server-api-overview
 
 
 ## Acknowledgements
-This project was inspired by, and evolved from, https://github.com/berkayk/laravel-onesignal
+This project was inspired by, and evolved from, https://github.com/berkayk/laravel-onesignal