Update README.md

Author: mpociot

README.md

@@ -7,6 +7,8 @@
 
 Bring the power of WebSockets to your Laravel application. Drop-in Pusher replacement, SSL support, Laravel Echo support and a debug dashboard are just some of its features.
 
+> If you want to learn how to create reusable PHP packages yourself, take a look at my upcoming [PHP Package Development](https://phppackagedevelopment.com) video course.
+
 ## Documentation
 
 For installation instructions, in-depth usage and deployment details, please take a look at the [official documentation](https://docs.beyondco.de/laravel-websockets/).