Improve searchable in `doctrine`

app/models/doctrine.rb

@@ -183,10 +183,8 @@ class Doctrine < ApplicationRecord
       paper_trail.originator.to_i
     end
 
-    join(:search_doc_date, :target => DoctrineJurisprudence, :type => :date, :join => { :from => :doctrine_id, :to => :id })
-    join(:search_year, :target => DoctrineJurisprudence, :type => :integer, :join => { :from => :doctrine_id, :to => :id })
-    join(:reference_number, :target => DoctrineJurisprudence, :type => :string, :join => { :from => :doctrine_id, :to => :id })
-
     date :created_at
+
+    string :headnote
   end
 end