do not verify SSD wipes

That doesn't change anything from non-SSD wipes and just takes more
time for no reason.

howto/retire-a-host.md

@@ -89,7 +89,7 @@ WARNING: this procedure doesn't cover the case where the disk is an
 SSD. See [this paper][] for details on how classic data scrubbing
 software might not work for SSDs. For now we use this:
 
-    nwipe --autonuke --method=random --rounds=2 /dev/nvme1n1
+    nwipe --autonuke --method=random --rounds=2 --verify=off /dev/nvme1n1
 
 When you return: