Best practices for making relationships immutable?

From the docs, it looks like we can make a resource read-only by using immutable, but, is there a similar option to restrict operations in a relationship?

Given the following

  # brand has-many motorcycles
  jsonapi_resources :brand 
  jsonapi_resources :motorcycle

I want to restrict the operations between brands/relationships/motorcycles so only GET is allowed.

I found a workaround doing the following, but I wonder if there is a better solution.

jsonapi_resources :brands do
  jsonapi_relationships only: [:get]
end
jsonapi_resources :motorcycles

If that's the case I'll gladly add a note to the README so others can find it too.

Thanks!

Start with the README and the jsonapi_relationships only: [:get] configuration shown in the issue, comparing it with the documented immutable option. Confirm whether this configuration is the supported way to allow only GET operations for the relationship, then document the guidance and example in the README.