docs(README.md): describe maintenance mode

fix: replace machines

docs: describe renewing certs

Merge pull request #1038 from caos/better-keepalived-settings

fix: avoid too many KeepaliveD IP failovers

fix: avoid too many KeepaliveD IP failovers

Merge pull request #1019 from caos/disable-yum-gpg-repochecks

fix: disable gpg checks for https yum repos

fix: disable gpg checks for https yum repos

Merge pull request #989 from caos/fix-writesecret-nilpointer

fix: omit k8s client when gitops mode, not crd

use ubuntu image

fix: omit k8s client when gitops mode, not crd