add assessement endpoint

app/models/assessment.rb

@@ -0,0 +1,23 @@
+# == Schema Information
+#
+# Table name: assessments
+#
+#  id           :bigint           not null, primary key
+#  observations :text
+#  params       :jsonb
+#  title        :string
+#  created_at   :datetime         not null
+#  updated_at   :datetime         not null
+#  user_id      :bigint           not null
+#
+# Indexes
+#
+#  index_assessments_on_user_id  (user_id)
+#
+# Foreign Keys
+#
+#  fk_rails_...  (user_id => users.id)
+#
+class Assessment < ApplicationRecord
+  belongs_to :user
+end