Force releasenotes warnings to be treated as errors
Force releasenotes warnings to be treated as errors

Ensure the releasenotes can always be built and rendered properly.

Change-Id: I78e09804d51416c045d3569ed7fe90eb77dc9b21

coreycb/horizon,redhat-openstack/horizon,NeCTAR-RC/horizon,noironetworks/horizon,ChameleonCloud/horizon,davidcusatis/horizon,redhat-openstack/horizon,Tesora/tesora-horizon,noironetworks/horizon,wolverineav/horizon,coreycb/horizon,bigswitch/horizon,gerrive/horizon,openstack/horizon,sandvine/horizon,django-leonardo/horizon,django-leonardo/horizon,davidcusatis/horizon,bigswitch/horizon,sandvine/horizon,yeming233/horizon,redhat-cip/horizon,yeming233/horizon,ChameleonCloud/horizon,BiznetGIO/horizon,Tesora/tesora-horizon,gerrive/horizon,redhat-openstack/horizon,openstack/horizon,davidcusatis/horizon,Mirantis/mos-horizon,NeCTAR-RC/horizon,noironetworks/horizon,sandvine/horizon,davidcusatis/horizon,NeCTAR-RC/horizon,wolverineav/horizon,Mirantis/mos-horizon,bac/horizon,gerrive/horizon,Tesora/tesora-horizon,yeming233/horizon,noironetworks/horizon,dan1/horizon-x509,redhat-cip/horizon,django-leonardo/horizon,Tesora/tesora-horizon,bac/horizon,dan1/horizon-x509,coreycb/horizon,redhat-openstack/horizon,gerrive/horizon,bac/horizon,BiznetGIO/horizon,BiznetGIO/horizon,NeCTAR-RC/horizon,redhat-cip/horizon,Mirantis/mos-horizon,openstack/horizon,django-leonardo/horizon,wolverineav/horizon,sandvine/horizon,BiznetGIO/horizon,redhat-cip/horizon,openstack/horizon,ChameleonCloud/horizon,bigswitch/horizon,ChameleonCloud/horizon,wolverineav/horizon,dan1/horizon-x509,yeming233/horizon,bac/horizon,bigswitch/horizon,coreycb/horizon,Mirantis/mos-horizon,dan1/horizon-x509