Change hostname description

Author: SNiemann15

modules/installation-ibm-z-user-infra-machines-iso.adoc

@@ -66,7 +66,7 @@ The rootfs image is the same for FCP and DASD.
 ... An empty string.
 ... The gateway.
 ... The netmask.
-... The machine host and domain name in the form `hostname.domainname`. Omit this value to let {op-system} decide.
+... The machine host and domain name in the form `hostname.domainname`. If you omit this value, {op-system} obtains the hostname through a reverse DNS lookup.
 ... The network interface name. If you omit this value, {op-system} applies the IP configuration to all available interfaces.
 ... If you use static IP addresses, specify `none`.
 ** For `coreos.inst.ignition_url=`, specify the Ignition file for the machine role. Use `bootstrap.ign`, `master.ign`, or `worker.ign`. Only HTTP and HTTPS protocols are supported.

modules/machine-user-infra-machines-ibm-z.adoc

@@ -84,7 +84,7 @@ $ curl -LO $(oc -n openshift-machine-config-operator get configmap/coreos-bootim
 ... An empty string.
 ... The gateway.
 ... The netmask.
-... The machine host and domain name in the form `hostname.domainname`. Omit this value to let {op-system} decide.
+... The machine host and domain name in the form `hostname.domainname`. If you omit this value, {op-system} obtains the hostname through a reverse DNS lookup.
 ... The network interface name. If you omit this value, {op-system} applies the IP configuration to all available interfaces.
 ... The value `none`.
 ** For `coreos.inst.ignition_url=`, specify the URL to the `worker.ign` file. Only HTTP and HTTPS protocols are supported.