[#27] Added migration file for comment counts.

Author: paulmckissock

db/migrate/20240701192701_add_comments_count_to_articles.rb

@@ -0,0 +1,5 @@
+class AddCommentsCountToArticles < ActiveRecord::Migration[7.1]
+  def change
+    add_column :articles, :comments_count, :integer
+  end
+end