Document image refresh API call.
Document image refresh API call.

Signed-off-by: Alberto Donato <3d6ca22374542c32836b344db03c69e81292ccc8@canonical.com>

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