Add comments to default config to explain Ubuntu deltas

[Mitchell Dzurick]

Hello, reading https://discourse.ubuntu.com/t/sshd-now-uses-socket-based-activation-ubuntu-22-10-and-later/30189/44 a great point is made here.

Can we put some comments in the default config explaining the deltas we make? This would be the most visible place for end-users.

[Nick Rosbrook (enr0n)]

We currently have:

```
Include /etc/ssh/sshd_config.d/*.conf

# When systemd socket activation is used (the default), the socket
# configuration must be re-generated after changing Port, AddressFamily, or
# ListenAddress.
#
# For changes to take effect, run:
#
# systemctl daemon-reload
# systemctl restart ssh.socket
#
#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

```

in the default sshd_config on oracular. I started an SRU for noble that was kicked out by a security update, but I will re-upload that soon.

Is this what you are looking for? Or something different?

[Mitchell Dzurick (mitchdz)]

Works for me, I just wanted to make this bug since I've seen some complaints (see the discourse link) to help raise awareness.