Tidy up release notes for Ussuri

...hanism-for-prometheus-customization-0b173ff7c63ca30f.yaml

...ow-custom-ceilometer-upgrade-params-c07eec4c1ef5a3d3.yaml

...s/notes/ansible-max-version-support-d74258eec27d3549.yaml

...es/bug-1846789-fix-fernet-bootstrap-36f87e36e4dc6ec9.yaml

...es/bug-1858773-manila-cephfs-driver-f6a75bd15c002363.yaml

releasenotes/notes/ceph-keys-vars-6857d19d291c401d.yaml

...tes/configure-certificate-authority-aa21fa88234b021e.yaml

...rtificate-authority-into-containers-860cbda3384dd731.yaml

...asenotes/notes/docker-image-pruning-fffcffa7e99c6e63.yaml

releasenotes/notes/drop-py27-509835da35f047b4.yaml

...notes/notes/encrypt-backend-haproxy-fb96285d74fb464c.yaml

...cute-rest-methods-inside-containers-ce2a1410dbdc71f3.yaml

...notes/external-ceph-cinder-template-40dc0bc07e717837.yaml

releasenotes/notes/external-ceph-users-2715eebf8a8df1af.yaml

...enotes/notes/feature-mergepwd-clean-18cbed4d39967e70.yaml

...issue-with-elasticsearch-kolla-logs-a0ba85d91d1a2c31.yaml

...notes/notes/fix-octavia-cert-config-28f0ef2799406957.yaml

...internal-external-self-signed-certs-c631a9d934d31fac.yaml

...tes/notes/horizon_keystone_dropdown-6b9b4e5e9a64f979.yaml

releasenotes/notes/implement-ovn-80b3a73e6c8a44e7.yaml