* nixos/tor: add hiddenServices option
This change allows to configure hidden services more conveniently.
* nixos/tor: fix default/example mixup
* nixos/tor: use docbook in documentation
Also use more elegant optionalString for optional strings.
* tor: seperate hidden service port by newline
* tor: better example for hidden service path
a path below /var/lib/tor is usually used for hidden services