fix dropbear instructions in readme

README.md

@@ -16,8 +16,9 @@ reboot
 
 
 # Unlock the disk after booting the server from disk:
-# Dropbear is configured on 222
-ssh -p 222 <fqdn> /bin/cryptroot-unlock
+# Dropbear is configured on 222 and only allows the user root
+ssh -p 222 root@<fqdn>
+cryptroot-unlock
 ```
 
 `setup.sh` executes the hardware specific template files, debootstraps and invokes the actual installer inside the fresh environment.