specs: Document some user.* keys
specs: Document some user.* keys

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

georghopp/lxd,stgraber/lxd,ollie314/lxd,jsavikko/lxd,Malizor/lxd,ericsnowcurrently/lxd,chrisglass/lxd,lxc/lxd,achanda/lxd,yura-pakhuchiy/lxd,akshaykarle/lxd,akshaykarle/lxd,akshaykarle/lxd,lxc/lxd,ollie314/lxd,Malizor/lxd,mjeanson/lxd,stgraber/lxd,georghopp/lxd,chrisglass/lxd,erikmack/lxd,techtonik/lxd,techtonik/lxd,yura-pakhuchiy/lxd,stgraber/lxd,jsavikko/lxd,atxwebs/lxd,hallyn/lxd,georghopp/lxd,Skarlso/lxd,hallyn/lxd,pcdummy/lxd,hallyn/lxd,hallyn/lxd,mjeanson/lxd,mjeanson/lxd,stgraber/lxd,Skarlso/lxd,yura-pakhuchiy/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,pcdummy/lxd,erikmack/lxd,lxc/lxd,hallyn/lxd,chrisglass/lxd,ericsnowcurrently/lxd,Skarlso/lxd,stgraber/lxd,erikmack/lxd,techtonik/lxd,atxwebs/lxd,stgraber/lxd,dustinkirkland/lxd,lxc/lxd,Malizor/lxd,ollie314/lxd,pcdummy/lxd,achanda/lxd,dustinkirkland/lxd,Skarlso/lxd,jsavikko/lxd,atxwebs/lxd,ericsnowcurrently/lxd,stgraber/lxd,atxwebs/lxd,achanda/lxd,dustinkirkland/lxd