docs(doc): update the description for nvs in dev setup doc (#14637)

* docs(doc): update the description for nvs in dev setup doc

Author: koji

DEV_SETUP.md

@@ -82,7 +82,7 @@ Close and re-open your terminal to confirm `nvs` is installed.
 nvs --version
 ```
 
-Now we can use nvs to install Node.js v18 and switch on `auto` mode, which will make sure Node.js v18 is used any time we're in the `opentrons` project directory.
+Now we can use `nvs` to install the currently required Node.js version set in `.nvmrc`. The `auto` command selects the correct version of Node.js any time we're in the `opentrons` project directory. Without `auto`, we would have to manually run `use` or `install` each time we work on the project.
 
 ```shell
 nvs add 18