Document Serializing Nested Archetypes

[Nicholas-Westby]

Would be good to cover how to serialize nested archetypes here: https://github.com/kgiszewski/ArchetypeManual/blob/master/06%20-%20Editing%20an%20Archetype%20in%20Code.md

For example, would be good to know what we should do when the nested Archetype has no fieldsets (e.g., serialize an Archetype with no fieldsets, serialize an Archetype with fieldsets set to an empty list, or a null value).

[kgiszewski]

Absolutely if you are up for it :)

[Nicholas-Westby]

Will definitely do that once life settles down a bit (that pesky thing that gets in the way of programming). Creating the nested Archetype as a new instance of ArchetypeModel seemed to work... I'll have to try out the other variations too (e.g., null, empty list, etc.).