Add include_total option to the README

Author: StefSchenkelaars

README.md

@@ -55,6 +55,11 @@ ApiPagination.configure do |config|
   config.per_page_param do |params|
     params[:page][:size]
   end
+ 
+  # Optional: Include the total and last_page link header
+  # By default, this is set to true
+  # Note: When using kaminari, this prevents the count call to the database
+  config.include_total = false 
 end
 ```