Fix hidden command in Nushell (#48)

The coditional check ran the mise hook but hid its exported command. It
was intended to prevent mise from running in scripts. In practice those
configs are skipped by default in scripts anyway.

getting-started.md

@@ -331,21 +331,15 @@ Since Nu does [not support `eval`](https://www.nushell.sh/book/how_nushell_code_
 ```nushell
 '
 let mise_path = $nu.default-config-dir | path join scripts mise.nu
-if $nu.is-interactive {
-  ^mise activate nu | save $mise_path --force
-}' | save $nu.env-path --append
-'
-if $nu.is-interactive {
-  use mise.nu
-}' | save $nu.config-path --append
+^mise activate nu | save $mise_path --force
+' | save $nu.env-path --append
+"\nuse mise.nu" | save $nu.config-path --append
 ```
 
 If you prefer to keep your dotfiles clean you can save it to a different directory then update `$env.NU_LIB_DIRS`:
 
 ```nushell
-'
-$env.NU_LIB_DIRS ++= ($mise_path | path dirname | to nuon)
-' | save $nu.env-path --append
+"\n$env.NU_LIB_DIRS ++= ($mise_path | path dirname | to nuon)" | save $nu.env-path --append
 ```
 
 #### Xonsh