Show related types when viewing one type

Imagine a scenario were we have an input type that is used in 3 different mutations. I communicate to my colleagues that I've changed the input type, perhaps making a field non-nullable.

When those developers look for the name of this input type in graphiql it would be very useful to also see where this type appears.

In the [live demo](http://graphql.org/swapi-graphql/) for example, if one views the type `Vehicle` GraphiQL could automatically tell us that this type appears in `VehicleConnectionEdge`, `vehicle(id)` and any others that I missed from a quick glance.