Rename foreign_key_on :related_resource option to :related

Author: lgebhardt

README.md

@@ -247,7 +247,7 @@ The association methods support the following options:
  * `relation_name` - the name of the relation to use on the model. A lambda may be provided which allows conditional selection of the relation based on the context.
 
 `has_one` associations support the additional option:
- * `foreign_key_on` - defaults to `:self`. To indicate that the foreign key is on the related resource specify `:related_resource`.
+ * `foreign_key_on` - defaults to `:self`. To indicate that the foreign key is on the related resource specify `:related`.
 
 Examples:
 

test/fixtures/active_record.rb

@@ -1092,8 +1092,8 @@ module V5
     class AuthorResource < JSONAPI::Resource
       attributes :name, :email
       model_name 'Person'
-      has_many :posts
-      has_one :author_detail, foreign_key_on: :related_resource
+      relationship :posts, to: :many
+      relationship :author_detail, to: :one, foreign_key_on: :related
 
       filter :name