Put clusterName in kustomize.yaml for the mariadb-operator.

The documentation currently has you ensure your servers have an FQDN, which
might lead some people to to give their cluster a name besides the default
cluster.local. If you don't put your actual cluster name here, you can't get
the MariaDB stuff deployed, so I put in 'cluster.local' to suggest that it
should get edited.

kustomize/mariadb-operator/kustomization.yaml

@@ -6,6 +6,7 @@ helmCharts:
     repo: https://mariadb-operator.github.io/mariadb-operator
     releaseName: mariadb-operator
     valuesInline:
+      clusterName: cluster.local
       webhook:
         cert:
           certManager: