I'm going to represent the critical opinion and say: this is cute and I like the idea in theory, but if I encountered this in the wild, I would just leave the page. I explore most informational websites with a mouse or a touchscreen - I don't want to type to navigate your website! A middleground might be to make the commands clickable, so that clicking on "help" automatically inserts and runs it, and clicking on any…
Personally I'd have gone for a 90s TUI-style hypertext presentation. But, like I said, nice work!