change cloumn auth_token to app_token in employees

db/migrate/20200114103715_change_column_auth_token_to_app_token.rb

@@ -0,0 +1,5 @@
+class ChangeColumnAuthTokenToAppToken < ActiveRecord::Migration[5.1]
+  def change
+    rename_column :employees, :auth_token, :app_token
+  end
+end