Rails - How to implement Routes for Many-to-Many

https://stackoverflow.com/questions/31258275/rails-4-how-to-implement-routes-for-a-many-to-many-relationship

https://edgeguides.rubyonrails.org/routing.html#routing-concerns

https://edgeapi.rubyonrails.org/classes/ActionDispatch/Routing/Mapper/Concerns.html#method-i-concern