Better documentation about how to $persist() a record with Many-to-many relationships

[leonceaklin]

During the setup of my first vuex-orm project with graphql I could not find a good example on how to $persist() records with many-to-many relationships. For example the documentation says that the relationships "are filtered out" but that doesn't seem to be true if they are eager loaded. Until now I couldn't figure out the workflow of presisting such a record correctly so I would be glad if somebody more experienced could add an entry to the documentation which explains this, preferably with a method which is commonly used within GraphQL systems. For example, I use Lighthouse for Laravel as GraphQL framework and its documentation recommends this method to store many-to-many relationships.