annotate approver and approval models

app/models/approval.rb

+# == Schema Information
+#
+# Table name: approvals
+#
+#  id               :integer          not null, primary key
+#  merge_request_id :integer          not null
+#  user_id          :integer          not null
+#  created_at       :datetime
+#  updated_at       :datetime
+#
+
 class Approval < ActiveRecord::Base
   belongs_to :user
   belongs_to :merge_request

app/models/approver.rb

+# == Schema Information
+#
+# Table name: approvers
+#
+#  id          :integer          not null, primary key
+#  target_id   :integer          not null
+#  target_type :string(255)
+#  user_id     :integer          not null
+#  created_at  :datetime
+#  updated_at  :datetime
+#
+
 class Approver < ActiveRecord::Base
   belongs_to :target, polymorphic: true
   belongs_to :user