There is a mail action you can trigger from a rule or from server-side JavaScript. The mail action takes a mail body template which can be used to provide a link to the document.
In the current version of Alfresco there is no way to run this action against multiple documents using the out-of-the-box user interface. However, this could be written as a customization because the document list supports selecting one or more documents and performing bulk operations on the the selected documents.