Update README with new "Support us" section

Author: AdrianMrn

README.md

@@ -70,6 +70,10 @@ Tests: 1, Assertions: 1, Failures: 1.
 
 ## Support us
 
+Learn how to create a package like this one, by watching our premium video course:
+
+[![Laravel Package training](https://spatie.be/github/package-training.jpg)](https://laravelpackage.training)
+
 We invest a lot of resources into creating [best in class open source packages](https://spatie.be/open-source). You can support us by [buying one of our paid products](https://spatie.be/open-source/support-us).
 
 We highly appreciate you sending us a postcard from your hometown, mentioning which of our package(s) you are using. You'll find our address on [our contact page](https://spatie.be/about-us). We publish all received postcards on [our virtual postcard wall](https://spatie.be/open-source/postcards).