Clarify documentation on using field extension options
Clarify documentation on using field extension options

I was puzzled on how to retrieve the options passed to an `extension`, since the hash passed to `after_resolve` simply did not contain them. I poked around at the test specs and realized that `options` is actually an attribute on the `GraphQL::Schema::FieldExtension`, not a function parameter.
nevesenin/graphql-ruby,rmosolgo/graphql-ruby,rmosolgo/graphql-ruby,rmosolgo/graphql-ruby,nevesenin/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,nevesenin/graphql-ruby