docs(readme): refresh settings preview

Author: josteinhanssen

README.md

@@ -168,6 +168,8 @@ Open **Noctalia Settings → Plugins → Caffeinate** to:
 - hide the bar widget when no session is current;
 - reset all plugin settings to their defaults.
 
+![Caffeinate settings showing the command alias, inactive widget behavior, and duration presets](caffeinate/preview.png)
+
 The canonical `>caffeinate` prefix is always available. Prefix collisions are
 resolved by Noctalia using provider registration order, so choose another
 alias if `>c` is already claimed in your setup.