Make ‘by month’ heading bold on usage
Make ‘by month’ heading bold on usage

So that it has the same visual weight as the other headings of the same
level (ie ‘Emails’ and ‘Text messages’).

alphagov/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin