Add Docker course link in free-courses-en (#10429)

courses/free-courses-en.md

@@ -615,6 +615,7 @@
 
 ### Docker
 
+* [Complete Docker Course - From BEGINNER to PRO!](https://www.youtube.com/watch?v=RqTEHSBrYFw) - DevOps Directive
 * [Deploying Containerized Applications Technical Overview](https://www.udemy.com/course/deploying-containerized-applications-technical-overview) - Red Hat
 * [Docker](https://www.youtube.com/playlist?list=PLhW3qG5bs-L99pQsZ74f-LC-tOEsBp2rK) - Raghav Pal
 * [Docker Essentials](https://cognitiveclass.ai/courses/docker-essentials) - CognitiveClass.ai