lxc-copy: update help to include hook options
lxc-copy: update help to include hook options

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@mailbox.org>

terceiro/lxc,LynxChaus/lxc,ysbnim/lxc,aeris/lxc,QingweiPeterLan/cs188-lxc,cjwatson/lxc,aeris/lxc,hfuCN/lxc,caglar10ur/lxc,LynxChaus/lxc,QingweiPeterLan/cs188-lxc,hallyn/lxc,QingweiPeterLan/cs188-lxc,GreatFruitOmsk/lxc,ysbnim/lxc,hallyn/lxc,cjwatson/lxc,thmo/lxc,tych0/lxc,hallyn/lxc,caglar10ur/lxc,tych0/lxc,caglar10ur/lxc,akshaykarle/lxc,federicobriata/lxc,federicobriata/lxc,tych0/lxc,GreatFruitOmsk/lxc,hfuCN/lxc,thmo/lxc,GreatFruitOmsk/lxc,LynxChaus/lxc,akshaykarle/lxc,thmo/lxc,aeris/lxc,ss1h2a3tw/lxc,cjwatson/lxc,hfuCN/lxc,terceiro/lxc,ysbnim/lxc,ss1h2a3tw/lxc,terceiro/lxc,federicobriata/lxc,akshaykarle/lxc,ss1h2a3tw/lxc