Currently on BIM 360's mobile app you are unable to share documents from directly within the app. Having a share button that could open up your email and send that document (with markups) that you are in as an attachment would be helpful.
Let's say you are walking a floor (A101) with an architect and this results in several markups on A101. It would be helpful to be able to share that document from the mobile app to send directly to the architect (or anybody else who may not have access to BIM 360) via email as an attachment.