update arch install docs, now we can use release version of cairocffi
update arch install docs, now we can use release version of cairocffi

Closes #529

kynikos/qtile,flacjacket/qtile,xplv/qtile,zordsdavini/qtile,ramnes/qtile,farebord/qtile,andrewyoung1991/qtile,frostidaho/qtile,EndPointCorp/qtile,aniruddhkanojia/qtile,soulchainer/qtile,nxnfufunezn/qtile,andrewyoung1991/qtile,kopchik/qtile,w1ndy/qtile,dequis/qtile,qtile/qtile,himaaaatti/qtile,frostidaho/qtile,qtile/qtile,nxnfufunezn/qtile,farebord/qtile,kseistrup/qtile,ramnes/qtile,soulchainer/qtile,de-vri-es/qtile,kiniou/qtile,dequis/qtile,xplv/qtile,w1ndy/qtile,tych0/qtile,jdowner/qtile,rxcomm/qtile,kseistrup/qtile,kiniou/qtile,aniruddhkanojia/qtile,apinsard/qtile,encukou/qtile,cortesi/qtile,de-vri-es/qtile,apinsard/qtile,tych0/qtile,kynikos/qtile,StephenBarnes/qtile,EndPointCorp/qtile,jdowner/qtile,cortesi/qtile,himaaaatti/qtile,rxcomm/qtile,flacjacket/qtile,StephenBarnes/qtile,zordsdavini/qtile,encukou/qtile,kopchik/qtile