[racket] thank you for typed racket

I do want to say that, despite some troubles I've been having with
Typed Racket, it's still awesome.  I'm building another prototype
Racket->JS compiler, and because it's still very experimental, I find
myself having to change the data types a lot.  I'm using Typed Racket
to code it, and it's been well worth the effort.  The type discipline
has been extraordinarily helpful in catching me as I'm iterating the
design of the data structures.  So thank you to everyone who's been
contributing to Typed Racket!