Change gitlab to gitlab_image on data run and add tail, thanks Vincent Robert.

docker/Dockerfile

 # At this moment GitLab doesn't have official Docker images.
 # Build your own based on the Omnibus packages with the following commands.
 # The first commands assumes you're in the GitLab repo root directory.
-# Build: sudo docker build --tag gitlab_image docker/.
-# Data: sudo docker run --name gitlab_data gitlab /bin/true
-# Run: sudo docker run --detach --name gitlab --publish 8080:80 --publish 2222:22 --volumes-from gitlab_data gitlab_image
+# sudo docker build --tag gitlab_image docker/
+# sudo docker run --name gitlab_data gitlab_image /bin/true
+# sudo docker run --detach --name gitlab --publish 8080:80 --publish 2222:22 --volumes-from gitlab_data gitlab_image
+# sudo docker run -t --rm --volumes-from gitlab_data ubuntu tail -f /var/log/gitlab/reconfigure.log
 
 FROM ubuntu:14.04
 MAINTAINER Vincent Robert <vincent.robert@genezys.net>