Update dev env docs on libvirt-dev(el) requirement
Update dev env docs on libvirt-dev(el) requirement

Commit 8f505b85268adc226ec0a83826c2d13edcbe3d7c added
a test requirement on libvirt-python which requires
libvirt-dev(el) being installed, so update the docs
to add that package for the distro.

Change-Id: I7169d3c78a6babe6e20c0dc35874167d0bfee922

gooddata/openstack-nova,BeyondTheClouds/nova,bigswitch/nova,Stavitsky/nova,Juniper/nova,cernops/nova,adelina-t/nova,LoHChina/nova,klmitch/nova,yosshy/nova,mahak/nova,mmnelemane/nova,Stavitsky/nova,gooddata/openstack-nova,felixma/nova,viggates/nova,CEG-FYP-OpenStack/scheduler,whitepages/nova,maelnor/nova,eonpatapon/nova,isyippee/nova,CCI-MOC/nova,eayunstack/nova,ted-gould/nova,blueboxgroup/nova,hanlind/nova,mgagne/nova,varunarya10/nova_test_latest,mahak/nova,Francis-Liu/animated-broccoli,zaina/nova,alaski/nova,takeshineshiro/nova,tianweizhang/nova,raildo/nova,badock/nova,rajalokan/nova,cloudbase/nova,devendermishrajio/nova_test_latest,openstack/nova,gooddata/openstack-nova,cloudbase/nova,nikesh-mahalka/nova,j-carpentier/nova,akash1808/nova_test_latest,Metaswitch/calico-nova,sebrandon1/nova,shail2810/nova,akash1808/nova,klmitch/nova,tealover/nova,ruslanloman/nova,vmturbo/nova,tealover/nova,eonpatapon/nova,JianyuWang/nova,tangfeixiong/nova,rajalokan/nova,ted-gould/nova,projectcalico/calico-nova,whitepages/nova,badock/nova,cyx1231st/nova,fnordahl/nova,viggates/nova,silenceli/nova,mikalstill/nova,eayunstack/nova,phenoxim/nova,edulramirez/nova,phenoxim/nova,noironetworks/nova,edulramirez/nova,ruslanloman/nova,belmiromoreira/nova,devendermishrajio/nova,zhimin711/nova,watonyweng/nova,rahulunair/nova,CEG-FYP-OpenStack/scheduler,JioCloud/nova_test_latest,cernops/nova,dawnpower/nova,bgxavier/nova,shail2810/nova,cloudbase/nova-virtualbox,dims/nova,silenceli/nova,petrutlucian94/nova,devendermishrajio/nova_test_latest,devendermishrajio/nova,alexandrucoman/vbox-nova-driver,MountainWei/nova,j-carpentier/nova,BeyondTheClouds/nova,angdraug/nova,zhimin711/nova,Yusuke1987/openstack_template,hanlind/nova,Juniper/nova,JianyuWang/nova,CloudServer/nova,JioCloud/nova_test_latest,hanlind/nova,TwinkleChawla/nova,scripnichenko/nova,CloudServer/nova,zzicewind/nova,rahulunair/nova,openstack/nova,tudorvio/nova,nikesh-mahalka/nova,scripnichenko/nova,cloudbase/nova-virtualbox,rajalokan/nova,felixma/nova,vmturbo/nova,saleemjaveds/https-github.com-openstack-nova,CCI-MOC/nova,bgxavier/nova,mikalstill/nova,tangfeixiong/nova,affo/nova,varunarya10/nova_test_latest,dawnpower/nova,jianghuaw/nova,yatinkumbhare/openstack-nova,vmturbo/nova,mandeepdhami/nova,Metaswitch/calico-nova,yatinkumbhare/openstack-nova,gooddata/openstack-nova,bigswitch/nova,zzicewind/nova,LoHChina/nova,mgagne/nova,thomasem/nova,thomasem/nova,barnsnake351/nova,NeCTAR-RC/nova,mahak/nova,sebrandon1/nova,jeffrey4l/nova,iuliat/nova,Tehsmash/nova,tudorvio/nova,TwinkleChawla/nova,dims/nova,double12gzh/nova,sebrandon1/nova,maelnor/nova,rajalokan/nova,barnsnake351/nova,angdraug/nova,JioCloud/nova,Francis-Liu/animated-broccoli,isyippee/nova,cyx1231st/nova,orbitfp7/nova,cloudbase/nova,cernops/nova,vladikr/nova_drafts,iuliat/nova,alaski/nova,akash1808/nova,jianghuaw/nova,blueboxgroup/nova,JioCloud/nova,yosshy/nova,mandeepdhami/nova,Tehsmash/nova,alexandrucoman/vbox-nova-driver,affo/nova,rahulunair/nova,adelina-t/nova,Yusuke1987/openstack_template,berrange/nova,klmitch/nova,projectcalico/calico-nova,saleemjaveds/https-github.com-openstack-nova,joker946/nova,fnordahl/nova,noironetworks/nova,redhat-openstack/nova,MountainWei/nova,apporc/nova,virtualopensystems/nova,jeffrey4l/nova,Juniper/nova,double12gzh/nova,apporc/nova,klmitch/nova,mikalstill/nova,raildo/nova,joker946/nova,alvarolopez/nova,petrutlucian94/nova,alvarolopez/nova,tianweizhang/nova,akash1808/nova_test_latest,jianghuaw/nova,jianghuaw/nova,virtualopensystems/nova,redhat-openstack/nova,orbitfp7/nova,openstack/nova,zaina/nova,belmiromoreira/nova,takeshineshiro/nova,NeCTAR-RC/nova,kimjaejoong/nova,kimjaejoong/nova,watonyweng/nova,Juniper/nova,vladikr/nova_drafts,berrange/nova,BeyondTheClouds/nova,vmturbo/nova,mmnelemane/nova