I've added a feature whereby readers can subscribe to be notified by email when certain content is updated. This is primarily intended so readers can be made aware of potentially important changes to pages such as the Firefox configuration guides and a few others. All that is necessary to subscribe is your email address and you can unsubscribe any time. Notifications will be sent only when non-trivial updates are made.
You can find the subscribe form at the bottom of the page, just above the comments section. See this page for example.