So we use google docs, because they are frankly quite awesome collaborative documents.
One bad thing though, they can't be annotated by h in the editing view. However, it is REALLY EASY to publish google doc to the web (instructions below).
The best thing about g-docs that have been published to the web is that they can then be annotated with Hypothes.is! #dogfooding
Note: under published content & settings, there is an option to make it so people will have to sign in with the appropriate google account.