Update ks-addon.cfg example in update-iso.sh to Debian

[Eric MacDonald]

Brief Description
-----------------
The example ks-addon.cfg shown in the update-iso.sh script depicts the CentOS way of configuring "initial IP interface at boot time by defining a VLAN on an Ethernet interface and has it use DHCP to request an IP address". WRCP 22.12 is Debian-only.

This bug report calls for that example help output be updated to reflect what networking interface setup would look like in Debian.

Severity
--------
Minor

Steps to Reproduce
-------------------
update-iso.sh --help

Expected Behavior
-----------------
The kickstart addon example should show an example that works in Debian.

Actual Behavior
---------------
The kickstart addon example shows an example that works in CentOS.

Reproducibility
---------------
100% Reproducible

System Configuration
--------------------
Any

Load info (eg: 2022-03-10_20-00-07)
---------
Any Debian load prior to the date of this bug report

Last Pass
---------
Test Escape with Debian changes.

Timestamp/Logs
--------------
N/A

Alarms
------
N/A

Test Activity
-------------
Normal Use

Workaround
----------
none

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/utilities/+/885877

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/utilities/+/885877
Committed: https://opendev.org/starlingx/utilities/commit/eefc2de70cc022304ba64fa8aa44b47a47443f70
Submitter: "Zuul (22348)"
Branch: master

commit eefc2de70cc022304ba64fa8aa44b47a47443f70
Author: Eric MacDonald <email address hidden>
Date: Mon Jun 12 13:27:48 2023 +0000

    Update update-iso.sh script with Debian network interface setup example

    The functional changes made to update-iso.sh over the transition from
    CentOS to Debian did not change the example in the tool's help output.

    This update modifies the network setup example in the update-iso.sh
    script to reflect the method used in Debian.

    Test Plan: Create a ks-addon.cfg script and add it to the iso
               using the update-iso.sh script.

    PASS: Run the update-iso.sh to add the ks-addon.cfg file
    PASS: Verify help output content and format
    PASS: Verify addon execution and interface file setup over USB install
    PASS: Verify addon execution and interface setup over pxeboot install
          ... with pxeboot addon support added to the kickstart
    PASS: Verify network scripts created properly on install
    PASS: Verify networking automatically setup over post install reboot
          ... using the example provided in this update

    Closes-Bug: 2023486
    Change-Id: I42d13c1ef0ad12b435c52c1bb312a21f30cf7fcd
    Signed-off-by: Eric MacDonald <email address hidden>