Fix NU_OVERLAYS pre_prompt hook example (#2008)

Author: hoel-bagard

cookbook/setup.md

@@ -105,7 +105,7 @@ currently activated.
 ```nu
 # set NU_OVERLAYS with overlay list, useful for starship prompt
 $env.config.hooks.pre_prompt = ($env.config.hooks.pre_prompt | append {||
-  let overlays = overlay list | range 1..
+  let overlays = overlay list | slice 1..
   if not ($overlays | is-empty) {
     $env.NU_OVERLAYS = $overlays | str join ", "
   } else {