Fix usage message.
Fix usage message.

griffithlab/regtools,gatoravi/regtools,gatoravi/regtools,griffithlab/regtools,gatoravi/regtools,griffithlab/regtools,gatoravi/regtools,griffithlab/regtools,tabbott/regtools,tabbott/regtools,tabbott/regtools,griffithlab/regtools,griffithlab/regtools,tabbott/regtools,tabbott/regtools,gatoravi/regtools