Reek: I don't know why it thinks that parameter is unused

Mysterious. I'll just exclude it
API Documentation for Model
API Documentation for Collection
API documentation for Configuration
API Documentation for DocumentModelMapper
API documentation for Query
Declared the Railtie to be part of the private API

This is not interesting for a user of Guacamole. It just does
stuff to introduce Guacamole to Rails.
Documentation for tiny things