Make it clear that the contents of product.img and updates.img comes
from the install root, not from the build host's filesystem.
Resolves: rhbz#1272361
With these templates if a package has installed files in
/usr/share/lorax/product or /usr/share/lorax/updates/ they will be used
to create product.img and/or updates.img which will be included in the
images/ directory of the iso and of the final output tree.
These can be used to customize the installation environment or provide
updates. See README.product for current documentation.
Related: rhbz#1202278