doc/configuration: add missing pci options for gpu
doc/configuration: add missing pci options for gpu

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@canonical.com>

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