fix doc indentation (it broke the HTML)

Change-Id: I833d2a36962278afd02f6efb409aebcf97e09deb
Reviewed-on: http://gerrit.aldebaran.lan:8080/15772
Tested-by: gerrit
Reviewed-by: dmerejkowsky <dmerejkowsky@aldebaran-robotics.com>
Reviewed-by: sbarthelemy <sbarthelemy@aldebaran-robotics.com>
Tested-by: sbarthelemy <sbarthelemy@aldebaran-robotics.com>