Add documentation and test for subfactory using "factory_parent" attribute

Add documentation on how to use a LazyAttribute in a SubFactory and poke
the "factory_parent" attribute to indirectly derive the value of a field
on the child factory from a field on the parent factory. This commit adds
an example to recipes that explains how it can be done. It also adds a
test to make sure that this feature continues to work as is now described
in the documentation.

0 files changed, 0 insertions, 0 deletions