add user document model

app/models/user_document.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: user_documents
+#
+#  id         :bigint           not null, primary key
+#  status     :string           not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#  user_id    :bigint           not null
+#
+# Indexes
+#
+#  index_user_documents_on_user_id  (user_id)
+#
+# Foreign Keys
+#
+#  fk_rails_...  (user_id => users.id)
+#
+class UserDocument < ApplicationRecord
+  extend Enumerize
+
+  belongs_to :user
+  has_one_attached :image
+
+  enumerize :status,
+    in: [:pending_review, :approved, :refused],
+    default: :pending_review
+end