How to Generate the linaro-***.img.gz?

Hi. How are the filesystem images built found in this location?:
https://snapshots.linaro.org/96boards/dragonboard820c/linaro/debian/

Are there instructions to build these?

Thanks,
Kim

Debian images are generated with FAI tool :Enable wcn36xx/wifi in FAI built image - #2 by ndec

This is helpful! Thanks,
Kim