update JSON adapter pagination links

docs/howto/add_pagination_links.md

@@ -74,32 +74,30 @@ ActiveModelSerializers pagination relies on a paginated collection with the meth
 
 If you are using `JSON` adapter, pagination links will not be included automatically, but it is possible to do so using `meta` key.
 
-In your action specify a custom serializer.
+Add this method to your base API controller.
-```ruby
-render json: @posts, serializer: PaginatedSerializer, each_serializer: PostPreviewSerializer
-```
 
-And then, you could do something like the following class.
 ```ruby
-class PaginatedSerializer < ActiveModel::Serializer::CollectionSerializer
+def pagination_dict(object)
-  def initialize(object, options={})
+  {
-    meta_key = options[:meta_key] || :meta
+    current_page: object.current_page,
-    options[meta_key] ||= {}
+    next_page: object.next_page,
-    options[meta_key] = {
+    prev_page: object.prev_page,
-      current_page: object.current_page,
+    total_pages: object.total_pages,
-      next_page: object.next_page,
+    total_count: object.total_count
-      prev_page: object.prev_page,
+  }
-      total_pages: object.total_pages,
-      total_count: object.total_count
-    }
-    super(object, options)
-  end
 end
 ```
+
+Then, use it on your render method.
+
+```ruby
+render json: posts, meta: pagination_dict(posts)
+```
+
 ex.
 ```json
 {
-  "articles": [
+  "posts": [
     {
       "id": 2,
       "title": "JSON API paints my bikeshed!",