Add expiration / checking timer

My problem is keeping my articles up to date.

For example, I may write documentation on a feature that is due to evolve, for example in 6 months' time.

The idea would be to be able to give an expiry date / timer to an article so as to receive a notification looking like : "Hey, your article xxx was written 6 months ago and needs proofreading. Make sure it's still up to date: [url of the article]

Thanks