docs(sterni/machines/ingeborg): add example ssh config for unlock

Mostly it's important (which I did this time at least) to remember that
with how things work at the moment, the initrd sshd is only reachable
via IPv4.

Change-Id: Ie9a87b6a38b2e128a8a2141d2221bbe7cfe24cdb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12792
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI

users/sterni/machines/ingeborg/network.nix

@@ -18,6 +18,13 @@ in
       initrd.network = {
         enable = true;
         ssh = {
+          # ssh_config:
+          # Host ingeborg-unlock
+          #     User root
+          #     HostName ingeborg.sterni.lv
+          #     AddressFamily inet # kernel commandline only gives ipv4
+          #     Port 22
+          #     UserKnownHostsFile /home/lukas/.ssh/initrd_known_hosts
           enable = true;
           authorizedKeys = depot.users.sterni.keys.all;
           hostKeys = [