[GSS](7.3.z) Use of deprecated command write-local-domain-controller in documentation

Execute the following command to configure the host controller to act as the new domain controller.

/host=HOST_NAME:write-local-domain-controller

[domain@127.0.0.1:19990 /] /host=backup:write-local-domain-controller
{
    "outcome" => "success",
    "result" => undefined,
    "response-headers" => {
        "warnings" => [{
            "warning" => "WFLYCTL0449: Operation write-local-domain-controller against the resource at address /host=backup is deprecated, and it might be removed in future version. See the the outpu
t of the read-operation-description operation to learn more about the deprecation.",
            "level" => "WARNING",
            "operation" => {
                "address" => [("host" => "backup")],
                "operation" => "write-local-domain-controller"
            }
        }],
        "process-state" => "reload-required"
    },
    "server-groups" => undefined
}

[domain@127.0.0.1:19990 /] /host=backup:write-attribute(name=domain-controller.local, value={})
{
    "outcome" => "success",
    "result" => undefined,
    "server-groups" => undefined,
    "response-headers" => {"process-state" => "reload-required"}
}

$ diff -u host-slave.xml.org host-slave.xml
--- host-slave.xml.org	2021-03-05 10:44:55.529909903 +0900
+++ host-slave.xml	2021-03-05 11:40:15.578969067 +0900
@@ -62,11 +62,11 @@
         </management-interfaces>
     </management>
     <domain-controller>
-        <remote security-realm="ManagementRealm">
+        <local>
             <discovery-options>
                 <static-discovery name="primary" protocol="${jboss.domain.master.protocol:remote+http}" host="${jboss.domain.master.address:127.0.0.1}" port="${jboss.domain.master.port:9990}"/>
             </discovery-options>
-        </remote>
+        </local>
     </domain-controller>
     <interfaces>
         <interface name="management">