Add comments'

db/migrate/20211216185503_create_comments.rb

@@ -0,0 +1,10 @@
+class CreateComments < ActiveRecord::Migration[7.0]
+  def change
+    create_table :comments do |t|
+      t.references :article, null: false, foreign_key: true
+      t.text :content
+
+      t.timestamps
+    end
+  end
+end