Updating Horizon contributing docs 
Updating Horizon contributing docs 

Updating Horizon contributing docs to include User Experience
and Persona Working Group details.

Change-Id: I6f19372b419f882f7d0d6485b90ad165df25fd2c

openstack/horizon,VaneCloud/horizon,tellesnobrega/horizon,dan1/horizon-x509,Mirantis/mos-horizon,BiznetGIO/horizon,blueboxgroup/horizon,django-leonardo/horizon,karthik-suresh/horizon,redhat-cip/horizon,vladryk/horizon,gerrive/horizon,coreycb/horizon,tsufiev/horizon,watonyweng/horizon,j4/horizon,xinwu/horizon,karthik-suresh/horizon,maestro-hybrid-cloud/horizon,bigswitch/horizon,henaras/horizon,tellesnobrega/horizon,davidcusatis/horizon,RudoCris/horizon,gerrive/horizon,redhat-cip/horizon,redhat-openstack/horizon,RudoCris/horizon,yeming233/horizon,yjxtogo/horizon,noironetworks/horizon,Daniex/horizon,yeming233/horizon,tqtran7/horizon,anthonydillon/horizon,henaras/horizon,blueboxgroup/horizon,xinwu/horizon,endorphinl/horizon-fork,damien-dg/horizon,Dark-Hacker/horizon,openstack/horizon,FNST-OpenStack/horizon,VaneCloud/horizon,yjxtogo/horizon,wolverineav/horizon,sandvine/horizon,pranavtendolkr/horizon,agileblaze/OpenStackTwoFactorAuthentication,icloudrnd/automation_tools,eayunstack/horizon,kfox1111/horizon,Dark-Hacker/horizon,tsufiev/horizon,BiznetGIO/horizon,blueboxgroup/horizon,icloudrnd/automation_tools,CiscoSystems/horizon,agileblaze/OpenStackTwoFactorAuthentication,pranavtendolkr/horizon,j4/horizon,Solinea/horizon,wolverineav/horizon,saydulk/horizon,NeCTAR-RC/horizon,yeming233/horizon,NeCTAR-RC/horizon,vladryk/horizon,dan1/horizon-x509,mandeepdhami/horizon,mandeepdhami/horizon,promptworks/horizon,Metaswitch/horizon,kfox1111/horizon,newrocknj/horizon,icloudrnd/automation_tools,luhanhan/horizon,eayunstack/horizon,dan1/horizon-x509,ChameleonCloud/horizon,idjaw/horizon,anthonydillon/horizon,Tesora/tesora-horizon,openstack/horizon,endorphinl/horizon-fork,ChameleonCloud/horizon,doug-fish/horizon,redhat-openstack/horizon,RudoCris/horizon,henaras/horizon,saydulk/horizon,bigswitch/horizon,Metaswitch/horizon,mdavid/horizon,izadorozhna/dashboard_integration_tests,noironetworks/horizon,endorphinl/horizon,promptworks/horizon,coreycb/horizon,j4/horizon,blueboxgroup/horizon,django-leonardo/horizon,NCI-Cloud/horizon,VaneCloud/horizon,vladryk/horizon,bac/horizon,karthik-suresh/horizon,mandeepdhami/horizon,mdavid/horizon,saydulk/horizon,sandvine/horizon,davidcusatis/horizon,endorphinl/horizon,mandeepdhami/horizon,eayunstack/horizon,django-leonardo/horizon,watonyweng/horizon,Dark-Hacker/horizon,openstack/horizon,idjaw/horizon,orbitfp7/horizon,Hodorable/0602,wangxiangyu/horizon,Metaswitch/horizon,orbitfp7/horizon,redhat-cip/horizon,orbitfp7/horizon,ChameleonCloud/horizon,mdavid/horizon,xinwu/horizon,maestro-hybrid-cloud/horizon,newrocknj/horizon,idjaw/horizon,dan1/horizon-proto,CiscoSystems/horizon,vladryk/horizon,BiznetGIO/horizon,Mirantis/mos-horizon,bigswitch/horizon,FNST-OpenStack/horizon,Tesora/tesora-horizon,promptworks/horizon,kfox1111/horizon,damien-dg/horizon,wangxiangyu/horizon,xinwu/horizon,kfox1111/horizon,Hodorable/0602,FNST-OpenStack/horizon,davidcusatis/horizon,tellesnobrega/horizon,tellesnobrega/horizon,Tesora/tesora-horizon,davidcusatis/horizon,dan1/horizon-proto,RudoCris/horizon,Metaswitch/horizon,bigswitch/horizon,Mirantis/mos-horizon,liyitest/rr,Daniex/horizon,bac/horizon,tqtran7/horizon,takeshineshiro/horizon,promptworks/horizon,coreycb/horizon,watonyweng/horizon,agileblaze/OpenStackTwoFactorAuthentication,liyitest/rr,anthonydillon/horizon,CiscoSystems/horizon,pranavtendolkr/horizon,ChameleonCloud/horizon,tqtran7/horizon,Tesora/tesora-horizon,dan1/horizon-proto,Solinea/horizon,django-leonardo/horizon,wangxiangyu/horizon,takeshineshiro/horizon,Solinea/horizon,pranavtendolkr/horizon,CiscoSystems/horizon,wolverineav/horizon,philoniare/horizon,coreycb/horizon,Hodorable/0602,redhat-openstack/horizon,luhanhan/horizon,dan1/horizon-x509,liyitest/rr,idjaw/horizon,doug-fish/horizon,wolverineav/horizon,izadorozhna/dashboard_integration_tests,gerrive/horizon,takeshineshiro/horizon,FNST-OpenStack/horizon,philoniare/horizon,maestro-hybrid-cloud/horizon,watonyweng/horizon,BiznetGIO/horizon,philoniare/horizon,agileblaze/OpenStackTwoFactorAuthentication,NCI-Cloud/horizon,tsufiev/horizon,noironetworks/horizon,luhanhan/horizon,doug-fish/horizon,Hodorable/0602,maestro-hybrid-cloud/horizon,Mirantis/mos-horizon,bac/horizon,Daniex/horizon,endorphinl/horizon,takeshineshiro/horizon,dan1/horizon-proto,yjxtogo/horizon,newrocknj/horizon,karthik-suresh/horizon,yjxtogo/horizon,yeming233/horizon,noironetworks/horizon,sandvine/horizon,saydulk/horizon,Daniex/horizon,anthonydillon/horizon,damien-dg/horizon,philoniare/horizon,Dark-Hacker/horizon,orbitfp7/horizon,damien-dg/horizon,henaras/horizon,liyitest/rr,luhanhan/horizon,endorphinl/horizon,NeCTAR-RC/horizon,gerrive/horizon,bac/horizon,NCI-Cloud/horizon,mdavid/horizon,tqtran7/horizon,tsufiev/horizon,sandvine/horizon,wangxiangyu/horizon,endorphinl/horizon-fork,Solinea/horizon,redhat-cip/horizon,j4/horizon,endorphinl/horizon-fork,NCI-Cloud/horizon,NeCTAR-RC/horizon,newrocknj/horizon,redhat-openstack/horizon,doug-fish/horizon,icloudrnd/automation_tools,VaneCloud/horizon