fix: Add slug to articles (#5500)

db/migrate/20220926164441_add_slug_to_article.rb

@@ -0,0 +1,21 @@
+class AddSlugToArticle < ActiveRecord::Migration[6.1]
+  def up
+    add_column :articles, :slug, :string
+
+    update_past_articles_with_slug
+
+    add_index :articles, :slug
+    change_column_null(:articles, :slug, false)
+  end
+
+  def down
+    remove_column(:articles, :slug)
+  end
+
+  def update_past_articles_with_slug
+    Article.all.each_with_index do |article, index|
+      slug = article.title.underscore.parameterize(separator: '-')
+      article.update!(slug: "#{slug}-#{index}")
+    end
+  end
+end