- Documents features of Patroni both existing and targeted for addition
  in GitLab 13.7 that control Patroni's behavior when the primary node
  resumes operation and rejoins the database cluster.

Related https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/5746

Related https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/5759

Closes https://gitlab.com/gitlab-org/gitlab/-/issues/290999Signed-off-by: Robert Marshall <rmarshall@gitlab.com>