[plt-scheme] Natural Language parsing in CS1

I agree with Eli (who knows more about this topic than we might imagine).

It is very difficult to make these kinds of NL parsers scale to any
complexity, and moreover, the kinds that do (those used in real
software today) use a very different approach, so it's not like
there's a smooth continuum from here to there.  It would actually be
somewhat misleading to show this and suggest that this is how real NL
parsers work, just with more of the same.

Shriram