Lorax now supports creation of product.img and updates.img as part of the build
process. This is implemented using the installimg command which will take the
contents of a directory and create a compressed archive from it. The x86, ppc,
ppc64le and aarch64 templates all look for /usr/share/lorax/product/ and
/usr/share/lorax/updates/ directories while creating the final install tree. If
there are files in those directories lorax will create images/product.img
and/or images/updates.img

These archives are just like an anaconda updates image -- they are copied over
the top of the filesystem at boot time so that you can drop in files to add to
or replace anything on the filesystem.

Anaconda has several places that it looks for updates, the one for product.img
is in /run/install/product.  For example, to add an installclass to Anaconda
you would put your custom class here:

/usr/share/lorax/product/run/install/product/pyanaconda/installclasses/custom.py

