* Simplify /windows to the bare minimum. Also remove the
/windows/tailscale.reg endpoint as its generated file is no longer
valid for current Tailscale versions.
* Update and simplify the windows documentation accordingly.
* Add a "Unattended mode" section to the troubleshooting section
explaining how to enable "Unattended mode" in the via the Tailscale
tray icon.
* Add infobox about /windows to the docs
Tested on Windows 10, 22H2 with Tailscale 1.72.0
Replaces: #1995
See: #2096
