update docker readme

roles/docker/README.md

@@ -19,14 +19,14 @@ This role is only tested on Fedora/CentOS machines.
 Variables
 ---------
 
-`container_user`: user name to run containers as (will be generated if not exists)
-`container_uid`: uid of above user name
-`container_group`: group name of container_user
-`container_gid`: gid of above group name
+`container_user`: user name to run containers as (will be generated if not exists)<br>
+`container_uid`: uid of above user name<br>
+`container_group`: group name of container_user<br>
+`container_gid`: gid of above group name<br>
 
 Automated pulls and purges are handled by systemd timers. Any valid [systemd timer calendar event expression](https://www.freedesktop.org/software/systemd/man/systemd.timer.html#OnCalendar=) may be passed to them:
 
-`docker_pull_timer`: weekly
+`docker_pull_timer`: weekly<br>
 `docker_purge_timer`: monthly
 
     global_env_vars: # will be set on any container which has include_global_env_vars: true