lxc/copy: Rework usage to be parsable by help2man
lxc/copy: Rework usage to be parsable by help2man

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

jsavikko/lxd,techtonik/lxd,stgraber/lxd,stgraber/lxd,Skarlso/lxd,hallyn/lxd,lxc/lxd,techtonik/lxd,lxc/lxd,hallyn/lxd,georghopp/lxd,mjeanson/lxd,pcdummy/lxd,lxc/lxd,Skarlso/lxd,lxc/lxd,pcdummy/lxd,erikmack/lxd,jsavikko/lxd,mjeanson/lxd,stgraber/lxd,atxwebs/lxd,Skarlso/lxd,pcdummy/lxd,stgraber/lxd,mjeanson/lxd,stgraber/lxd,techtonik/lxd,hallyn/lxd,georghopp/lxd,hallyn/lxd,stgraber/lxd,lxc/lxd,jsavikko/lxd,hallyn/lxd,atxwebs/lxd,stgraber/lxd,lxc/lxd,erikmack/lxd,atxwebs/lxd,Skarlso/lxd,georghopp/lxd,erikmack/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd