Sorry, did not type an s here:
Building an installer iso (build.sh --intaller). Does not.

That line should read: Building an installer iso (build.sh --installer). Does not.

It is only a typo, when I tried, the command was correct

This is not a bug. The directory "includes.chroot" is only for adding files to the Live image. It's not for the installer.

It's mentioned in the documentation, albeit it's not super explicit:

| With Live images, you have the option to include additional files or scripts
| in your build by overlaying them on the existing file-system, inside the
| includes.{chroot,binary,installer} directories, respectively.
| -- https://www.kali.org/docs/development/live-build-a-custom-kali-iso/

I'm not sure you can do that with the installer image

OK. That text below misleadme.
Thanks for your time.

You can configure virtually any aspect of your Kali ISO build, such as adding packages from outside of Kali network repositories, unattended installations to changing the default wallpaper. Our build-scripts provides a framework that uses a configuration set to automate and customize all aspects of building the images. The Kali Linux development team use the same build-scripts to produce the official Kali ISO releases.

The tool that builds the installer image is "simple-cdd". Therefore the directory "live-build-config/simple-cdd" contains things specific to the installer image.

The Debian wiki contains some information: https://wiki.debian.org/Simple-CDD/Howto. See the sections "Add custom files onto your installer CD" and "Add self-built packages to CD", maybe it can help.

Did you also check https://forums.kali.org/ ? Maybe there are some information, or maybe someone can help over there.

Good luck!