[racket] Wikipedia article update

Thanks for working on all these pages. I have edited these myself, and I have no objections to fixed. 

As for folding in the DrRacket/DrScheme page, I have serious doubts. We trained several hundred teachers and faculty colleagues who know us and who refer to us as the "DrScheme people". Even if you "fold in" the page, I recommend to keep the original and to use it as a base to point to the Racket page. 

-- Matthias