Merge "Following the new PTI for document build"

doc/requirements.txt

doc/source/admin/advanced-configuration.rst

doc/source/contributor/CONTRIBUTING.rst

doc/source/contributor/kolla-for-openstack-development.rst

doc/source/reference/bifrost.rst

doc/source/reference/central-logging-guide.rst

doc/source/reference/ceph-guide.rst

doc/source/reference/cinder-guide.rst

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

doc/source/reference/external-mariadb-guide.rst

doc/source/reference/hyperv-guide.rst

doc/source/reference/kuryr-guide.rst

doc/source/reference/manila-guide.rst

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

doc/source/reference/networking-guide.rst

doc/source/reference/nova-fake-driver.rst

doc/source/reference/swift-guide.rst

doc/source/reference/tacker-guide.rst

doc/source/reference/vmware-guide.rst

doc/source/reference/zun-guide.rst