Merge "doc: Start using openstackdoctheme's extlink extension"

doc/source/conf.py

doc/source/contributor/ptl-guide.rst

doc/source/contributor/release-management.rst

doc/source/contributor/running-tests.rst

doc/source/contributor/vagrant-dev-env.rst

doc/source/reference/bare-metal/ironic-guide.rst

doc/source/reference/compute/hyperv-guide.rst

doc/source/reference/compute/vmware-guide.rst

doc/source/reference/compute/xenserver-guide.rst

...source/reference/deployment-and-bootstrapping/bifrost.rst

doc/source/reference/networking/designate-guide.rst

doc/source/reference/networking/neutron-extensions.rst

doc/source/reference/networking/sriov.rst

doc/source/reference/shared-services/glance-guide.rst

doc/source/reference/shared-services/keystone-guide.rst

doc/source/reference/storage/cinder-guide-hnas.rst

doc/source/reference/storage/cinder-guide-quobyte.rst

doc/source/reference/storage/external-ceph-guide.rst

doc/source/reference/storage/manila-guide.rst

doc/source/reference/storage/manila-hnas-guide.rst