Function fetch_document 

pub(crate) async fn fetch_document(
    url: &Url,
    did: &str,
    private: PrivateAddresses,
) -> Result<Document, DocumentError>

Fetches did’s document from url, which didbot_identity::document_url gave for it, through a client pinned to the addresses it checked.

The caller refuses a url on a name this deployment answers to first: that fetch would be this server asking itself.