Add example schemas for "Model Relationships Between Documents"

[imlucas]

The docs define 3 examples for modeling relationships between documents, detailed here http://docs.mongodb.org/manual/applications/data-models-relationships/.

• Model One-to-One Relationships with Embedded Documents: Presents a data model that uses embedded documents to describe one-to-one relationships between connected data.
• Model One-to-Many Relationships with Embedded Documents: Presents a data model that uses embedded documents to describe one-to-many relationships between connected data.

[TZ2016]

@imlucas
The generator does not yet support document reference, but this is in my plan (though I haven't had a good idea about how to implement it).Should I work on this feature now?

[TZ2016]

This is done.