we are currently supporting MariaDB 10.1 as it is marked as stable and GA.
What specific feature or improvement are you looking for with the new version?
Is there any important feature available in MariaDB 10.2 that is not in MariaDB 10.1?
Apart from that, we try to keep our Docker containers available in Github updated to the latest stable version. Our Bitnami Docker MariaDB will be soon updated to match 10.2 series. Stay tuned at https://github.com/bitnami/bitnami-docker-mariadb