Improve cookbook setup env setup (#1972)

Resolves #1926

Author: Kissaki

cookbook/setup.md

@@ -11,15 +11,35 @@ There are other ways to view these values and variables, however setting up your
 
 ### Configure your path and other environment variables
 
-In order to configure your path in nushell you'll need to modify your `PATH` environment variable in your `config.nu` file. Open your `config.nu` file and put an entry in it like `$env.PATH = "path1;path2;path3"` ensuring that you use the proper path separation character, which is different by platform.
+In your `env.nu`, you can set up your environment.
 
-Alternately, if you want to append a folder to your `PATH` environment variable you can do that too using the `append` or `prepend` command like this:
+To configure environment variables, you use the `$env` variable:
 
 ```nu
-$env.PATH = ($env.PATH | split row (char esep) | append "some/other/path")
+$env.TITLE = 'Nu Test'
+$env.VALUE = 123
 ```
 
-For more detailed instructions, see the documentation about [environment variables](/book/environment.html#setting-environment-variables) and [PATH configuration](/book/configuration.html#path-configuration).
+To add paths to the `PATH` environment variable, you can append them:
+
+```nu
+$env.PATH ++= ['~/.local/bin']
+```
+
+Because you can append a list of paths, you can append multiple at once. You can also use subcommands to construct the paths in line.
+
+```nu
+$env.PATH ++= [ '~/.local/bin', ($env.CARGO_HOME | path join "bin") ]
+```
+
+Because PATH order makes a difference, you may want to *prepend* your paths instead, so that they take precedence over other executables with the same name:
+
+```
+use std/util "path add"
+path add '~/.local/bin'
+```
+
+For more information, see the documentation about [environment variables](/book/environment.html#setting-environment-variables) and [PATH configuration](/book/configuration.html#path-configuration).
 
 ### How to list your environment variables