Merge "Add support for Rocky Linux 8"

doc/source/contributor/testing.rst

doc/source/deployment.rst

doc/source/installation.rst

doc/source/support-matrix.rst

etc/kayobe/dnf.yml

etc/kayobe/globals.yml

etc/kayobe/infra-vms.yml

etc/kayobe/kolla.yml

etc/kayobe/overcloud-dib.yml

etc/kayobe/seed-vm.yml

playbooks/kayobe-infra-vm-base/pre.yml

...oks/kayobe-overcloud-host-configure-base/overrides.yml.j2

...ost-configure-base/tests/test_overcloud_host_configure.py

playbooks/kayobe-seed-vm-base/overrides.yml.j2

playbooks/kayobe-seed-vm-base/pre.yml

...asenotes/notes/support-rockylinux-8-1da50e2f97b918d5.yaml

roles/kayobe-ci-prep/tasks/main.yml

zuul.d/jobs.yaml

zuul.d/nodesets.yaml

zuul.d/project.yaml