Customer tailscale

[mihelich]

Provide customer instructions to access their robot remotely via Tailscale. Update and consolidate some of the common content around SSH configuration.

[guilhermedemouraa]

Everything looks great, thanks, Patrick!

PS: Should we also update cross-network settings?
I.e., instead of:

Host <robot-name>
  HostName <ip-address>
  User farm-ng-user-<username>

We would have:

Host <robot-name>
  HostName <robot-name>
  User farm-ng-user-<username>

[mihelich]

Host <robot-name>
  HostName <robot-name>

It would be nice if the customer could use the short name out-of-the-box, but with Tailscale node sharing, stuff like ping <robot-name> won't work automatically. Per sharing & MagicDNS, they need to use the robot's IP address or FQDN. I think that's a necessary limitation on the Tailscale side to avoid surprises like name collisions. I tried to be clear in the docs about what to replace <ip-address>, so I guess we'll see if this trips folks up.