Adds Kubernetes book (#6033)

Adds "Uncomplicating Kubernetes" by Jeferson Fernando

books/free-programming-books-subjects.md

@@ -198,6 +198,7 @@ Books that cover a specific programming language can be found in the  [BY PROGRA
 
 * [Docker Jumpstart](http://odewahn.github.io/docker-jumpstart/) - Andrew Odewahn
 * [Kubernetes Deployment & Security Patterns](https://resources.linuxfoundation.org/LF+Projects/CNCF/TheNewStack_Book2_KubernetesDeploymentAndSecurityPatterns.pdf) - Alex Williams (PDF)
+* [Uncomplicating Kubernetes](https://livro.descomplicandokubernetes.com.br/en/) - Jeferson Fernando
 
 
 ### Database