Add annotate_rb gem and annotate all models

app/models/puzzle.rb

@@ -1,3 +1,22 @@
+# == Schema Information
+#
+# Table name: puzzles
+#
+#  id         :integer          not null, primary key
+#  brand      :string
+#  name       :string
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#  contest_id :integer          not null
+#
+# Indexes
+#
+#  index_puzzles_on_contest_id  (contest_id)
+#
+# Foreign Keys
+#
+#  contest_id  (contest_id => contests.id)
+#
 class Puzzle < ApplicationRecord
   belongs_to :contest