Update relationships.md (#2212)
Update relationships.md (#2212)

* Update relationships.md

Rewrite some of the sentences. Add extra information and examples for clarification.

* Apply suggestions from code review

Co-Authored-By: Mike <a17fed27eaa842282862ff7c1b9c8395a26ac320@madebymike.com.au>

Co-authored-by: Mike <a17fed27eaa842282862ff7c1b9c8395a26ac320@madebymike.com.au>

keystonejs/keystone,keystonejs/keystone,keystonejs/keystone