Naming mismatching in ROS.org

[MrKeith99]

I have just notice that the documentation for dynamixel_workbench_msgs seems to be not properly updated in ROS.org.

In particular, XL.msg and XM.msg messages are pointing to different actuators.

In the GitHub repository, it looks like to be fine, but for the users who take as reference the ROS.org site for documentation might be a little bit confusing.

Thank you for your efforts.