[packages] Add fuchsia_packages directly to monolith.

Currently fuchsia_packages are added to monolith by way of the
preprocess_products.py script. This layer of indirection isn't necessary
and we may add them to monolith directly before processing.

Also, tidied contradictory documentation.

Change-Id: Idb48e60f3cc273aac2f04c2cf939318d5153ea8c
2 files changed