If you need to forward a document on to someone via email, you can do so from within the document and choose the format in which to send the document. You can also quickly send an email to everyone that a document is shared with, if you wish to communicate with all collaborators in one step. 

Emailing a document as an attachment

To send the current document as an attachment:

Emailing collaborators in a document

To send an email to everyone that a document is shared with: