doc: Add lxc.rootfs.backend in Japanese lxc.container.conf(5)
doc: Add lxc.rootfs.backend in Japanese lxc.container.conf(5)

Update for commit f903986

Signed-off-by: KATOH Yasufumi <512423cb3a4857a38f472862b51e4ab1a1730f06@jazz.email.ne.jp>

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