Update Nushell integration (#46)

* Update Nushell integration

Depends on jdx/mise#1763 in release.

* Automate reinstallation

Manually picked from starship/starship#5845.

getting-started.md

@@ -326,12 +326,26 @@ See [`MISE_FISH_AUTO_ACTIVATE=1`](/configuration#mise_fish_auto_activate1) for m
 
 #### Nushell
 
+Since Nu does [not support `eval`](https://www.nushell.sh/book/how_nushell_code_gets_run.html#eval-function) the initialization script is saved in `env.nu`:
+
+```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 $nu.config-path --append
+```
+
+If you prefer to keep your dotfiles clean you can save it to a different directory then update `$env.NU_LIB_DIRS`:
+
 ```nushell
-do {
-  let misepath = ($nu.config-path | path dirname | path join "mise.nu")
-  run-external mise activate nu --redirect-stdout | save $misepath -f
-  $"\nsource "($misepath)"" | save $nu.config-path --append
-}
+'
+$env.NU_LIB_DIRS ++= ($mise_path | path dirname | to nuon)
+' | save $nu.env-path --append
 ```
 
 #### Xonsh