Update README file

README.md

@@ -8,3 +8,20 @@ ansible-playbook -i $the-vm-you-want-to-configure, playbook.yml -e "username=$yo
 ```
 Please note the comma after the target. 
 
+Consider that the Docker repository and the username to login on the box are hardcoded in the playbook: 
+
+```
+- name: Install Docker and ContainerLab
+  hosts: all
+  become: true
+  vars:
+    docker:
+      registry_url: gitlab.geant.net:5005/docker/ci_registry   <<<<<<<<<<<<<<<<
+      username: "{{username }}"
+      private_token: "{{ secret_token}}"
+    nat_user: nat                 <<<<<<<<<<<<<<<<
+  roles:
+    - docker
+    - containerlab
+```
+