[cw-ctl] fix help message for schemadiff In global help (closes #2888538) The leading space make it appears on multiple line. The help content is a bit improved in the process.

#! /bin/sh -e
 
case "$1" in
    purge)
	rm -rf /etc/cubicweb.d/
	rm -rf /var/log/cubicweb/
	rm -rf /var/lib/cubicweb/
    ;;
esac
 
#DEBHELPER#
 
exit 0