Public documents are documents with the
isPublic flag set to true. They can be viewed by anyone, but can only be annotated by members of the document (by default).
Creating a public document
Editing a document to be public
Users have the ability to join public documents without an invite. This is required to annotate on the document.
To add the current user to a public document, use the joinDocument API.
id(string) The ID of the document to join.
Returns a promise that resolves to the new document object.
Throws an error if no user is signed in.