add note about possible error in docs

tsa/old/new-machine.mdwn

@@ -73,7 +73,9 @@
   puppet agent -t
   puppet agent -t
 
-* do on ud-replicate:
+* do on ud-replicate (possibly irrelevant: try without on next install
+  and fix this notes if ud-replicate works without):
+
   puppet agent -t
   echo alberti.torproject.org,alberti,db.torproject.org,db,38.229.70.7,2620:0:6b0:b:1a1a:0:26e5:4806 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAW1UewATLaASMo4mJoH+L8AgN1sJUIk/87z6OdrQNL9fDseLhFSPNg1LsL2Ep1ZbE22ieERHcaS4Mm8QrX9Y2VrUmFWK3jwz3+enhZkEzq7K+YKGKhUwSu+Cr+gKD1olKnw8COsZ4v5xkLh5Or854ZNJKRB84IF99P9TZ+0l/LyJCE3RVY/wV5FyhrweGmVUQVqsi7xv815uRNWjsiBWvizZddny8xaKsNTD7guo+nN9h9gjKzv6ktj/U9nbmBsBiLs4zZj7/6rfgXK020xOp63LXz8jRnDiISgHw+ERFYlmUYs04JXVrcI21jdnhzNCpLwSwBITQLSVPEaXJqO9v root@alberti > /etc/ssh/ssh_known_hosts &&
   ud-replicate