I have uploaded some documents and I do not worry about them. There however are 2 things to keep in mind:
- Attachments are not included in the backups. For details see here.
- It is not possible to view those documents inside Bitwarden. So to be able to do that you will have to store them on your local device. There is a feature request about this, but till now it has not even made it to the roadmap.