Hi ypatel ,
Thanks for your post.
Unfortunately, we don't have developer documentation. Nevertheless, all our code is well commented and formatted following the WordPress standards, so it shouldn't be difficult for a developer to find the needed hook.
Anyway, if you want to hook into the stock quantity change as you say in your other thread (and you don't use ATUM MultiInventory), the hook will belong to WooCommerce, not ATUM.
Bezt Regards,
José Andrés