README: Add shell setup instructions for nushell (#2916)

README.md

@@ -252,6 +252,24 @@ See [Advanced configuration](#advanced-configuration) for details and more confi
      ```
   </details>
 
+#### Nushell
+
+  <details>
+
+  Add the following lines to your `config.nu` to add Pyenv and its shims to your `PATH`.
+  Shell integration (completions and subcommands changing the shell's state)
+  isn't currently supported.
+
+  ~~~ nu
+  $env.PYENV_ROOT = "~/.pyenv" | path expand
+  if (( $"($env.PYENV_ROOT)/bin" | path type ) == "dir") {
+    $env.PATH = $env.PATH | prepend $"($env.PYENV_ROOT)/bin" }
+  $env.PATH = $env.PATH | prepend $"(pyenv root)/shims"
+  ~~~
+
+  </details>
+
+
 ### C. Restart your shell
 ----