- The MDCertificateAuthority directive can take more than one URL/name of
an ACME CA. This gives a failover for renewals when several consecutive attempts
to get a certificate failed. See REAME for details. - New directive MDRetryDelay to set the delay of retries. See README
for details. - New directive MDRetryFailover to set the number of errored attempts
before an alternate CA is selected for certificate renewals. See README
for details.