message: Document emits disconnect event.
diff: @@ -583,6 +583,7 @@ export class Document extends EventEmitter implements api.IDocument {
  this._deltaManager.on("disconnect", (nack: boolean) => {
  this.setConnectionState(api.ConnectionState.Disconnected, `Disconnected - nack === ${nack}`);
  + this.emit("disconnect");
  });
  this._deltaManager.on("error", (error) => {
  