Communities are able to load documents against suppliers on the Documents Tab which you can get to by going to Administration > Suppliers > Search and click into specific supplier > Documents tab.
By default the option Active Documents Only is enabled. When documents are deleted by the Community or the Supplier they will be marked Inactive.
To see these documents un-tick Active Documents Only.
To view the attachment(s) loaded with a document you can click on the paperclip icon to open the below pop-up. This will allow you to view (click on the eyeball icon) or download (click on the down arrow) the attachment(s).
To add a new document to the supplier you will need to go to the Documents tab and click +Add Document found above the Active Documents Only tick box.
Here you can enter the Purpose, Valid From Date, Valid To Date, tick Show to Buyers to enable it to be viewed by buyers and any Attachments. The Purpose field and attachment field are mandatory.