Notification of edited shared docs

Notification of edited shared docs

I see how to share my documents, and I see that I can easily email the others with whom I am sharing my documents. But when they change the document, I would like one of these to happen:
- Either provide a way for them to inform me that they have read and edited my document
or
- have the system automatically email all people on the "shared" list for a document that the document has been edited.

The first option is preferable, otherwise all people might receive an email every time a doc is saved -- and that would be too many emails.