Add some verbiage to help folks with the "script type" choice

[webchick]

I was having a blast with this project up until I got here and then I had to stop and ask ChatGPT what the heck this was asking lol:

It responded (more or less) to pick sh for macOS / Linux and ps for Windows. Assuming that's true, it would be nice if the option descriptions reflected that, so this point of friction goes away (and/or, #1132 happens, which makes this question vanish entirely).