Add comment to kickstart stating how LAT hook syntax errors are rendered

[Eric MacDonald]

Brief Description
-----------------
The Linux Assembly Tool parses a kickstart file containing various hook segments that are syntactically delineated with statements that start with '%'. The example below shows the start and end syntax of a hook block.

%post --interpreter=/bin/bash

<kickstart bash code goes here>

%end

If LAT detects a hook block syntax error it fails the install and renders it as a Permission error.

This Jira calls for 2 kickstart comments to be added saying
1. How hook syntax errors are rendered with a permission error.
2. the kickstart must end with a Line Feed after the last %end directive

Severity
--------
Minor: code comment only

Steps to Reproduce
------------------
Install a system after removing the LF from the end of the file.

Expected Behavior
------------------
install succeeds

Actual Behavior
----------------
install fails

Reproducibility
---------------
100% reproducible

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

Branch/Pull Time/Commit
-----------------------
N/A issue does not exist in master branch. Just need comments added to code.

Last Pass
---------
N/A

Timestamp/Logs
--------------
Run post install nochroot script /tmp/lat/lat_post_nochroot_script/10_script
+ IMAGE_ROOTFS=/sysroot/ostree/1
+ /tmp/lat/lat_post_nochroot_script/10_script
./lat-installer.sh: line 539: /tmp/lat/lat_post_nochroot_script/10_script: Permission denied
Run Kickstart Post Install Script failed in /sysroot/ostree/1

[ 349.536291] sysrq: Resetting

Test Activity
-------------
N/A

Workaround
----------
N/A

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/metal/+/922027