fix wrong linked image

Author: insectengine

_data/books.yaml

@@ -2,7 +2,7 @@
   description: "Build resilient and scalable, cloud-native, enterprise Java applications using the Quarkus framework."
   publish-date: January 2025
   authors: Martin Štefanko and Jan Martiška
-  thumbnail: quarkus-in-action.png
+  thumbnail: quarkus-in-action-ebook.png
   link: https://developers.redhat.com/e-books/quarkus-action
 - title: "Quarkus in Action"
   description: "Build resilient and scalable, cloud-native, enterprise Java applications using the Quarkus framework."