SSH: HashKnownHosts=no

HashKnownHosts provides an appearance of security but is actually
[easily crackable](https://github.com/chris408/known_hosts-hashcat) and
doesn't prevent leakage from other sources, such as the shell history or
SSH config.  Most importantly, it makes properly maintaining the list
tedious and error-prone by making it hard to remove changed keys and
impossible to remove obsolete entries, therefore possibly weakening
security.  Security should be enforced by password-protecting SSH keys
instead.

auto/ssh/config

@@ -1,3 +1,4 @@
 Host *
 	ForwardX11Trusted no
+	HashKnownHosts no
 	IdentitiesOnly yes