Add concise explanations
Add concise explanations

- explain functions in list.h
- let lxc_list_len() return size_t instead of int

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@mailbox.org>
Acked-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

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