net: update netdev dgram man page with unix socket

Add the description of "-netdev dgram" with a unix domain socket.
The code has been added but the man page has not been updated.

Fixes: 784e7a253104 ("net: dgram: add unix socket")
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
1 file changed