* Don't use `literalExample`, raw Nix values can directly be specified
as an option example which provides support for highlighting in the
manual as well.
* Escape shell args for `extraOptions`: I.e. the `-n` option might be
problematic as a longer notification command might be misinterpreted.
`xsslock` (which was originally packaged in 6cb1d1aaaf)
is a simple screensaver which connects a given screen locker (e.g.
`i3lock`) with `logind`. Whenever `loginctl lock-sessions` is invoked
the locker will be used to lock the screen. This works with its power
management features (e.g. `lid switch`) as well, so the PC can be locked
automatically when the lid is closed.
The module can be used like this:
```
{
services.xserver.enable = true;
programs.xss-lock.enable = true;
programs.xss-lock.lockerCommand = "i3lock";
}
```
