docs: added comment

Author: maxceem

migrations/2021-02-27-job-add-is-application-page-active-field.js

@@ -6,6 +6,8 @@ module.exports = {
   up: queryInterface => {
     return Promise.all([
       queryInterface.sequelize.query('ALTER TABLE bookings.jobs ADD is_application_page_active BOOLEAN NOT NULL DEFAULT false'),
+      // this command looks like does nothing, because we already set default value to `null` and this column cannot be `NULL`
+      // but we keep it as it was tested this way, and it looks harmful
       queryInterface.sequelize.query('UPDATE bookings.jobs SET is_application_page_active=false WHERE is_application_page_active is NULL'),
     ])
   },