Documented the optimizer.

(cherry picked from commit 8d6230956dc8c207c097a389fa1f0c7273bb55b7)

original commit: 536551ce5ec30081a4823a21512e8ecbfc448bbf

collects/typed-scheme/scribblings/optimization.scrbl

@@ -0,0 +1,21 @@
+#lang scribble/manual
+
+@begin[(require (for-label (only-meta-in 0 typed/racket)) scribble/eval
+		"utils.rkt" (only-in "quick.scrbl" typed-mod))]
+
+@(define the-eval (make-base-eval))
+@(the-eval '(require typed/racket))
+
+@title[#:tag "optimization"]{Optimization in Typed Racket}
+
+Typed Racket provides a type-driven optimizer that rewrites well-typed
+programs to potentially make them faster. It should in no way make
+your programs slower or unsafe.
+
+@section{Using the optimizer}
+
+Typed Racket's optimizer is not currently turned on by default. If you
+want to activate it, you must add the @racket[#:optimize] keyword when
+specifying the language of your program:
+
+@racketmod[typed/racket #:optimize]

collects/typed-scheme/scribblings/ts-guide.scrbl

@@ -19,6 +19,7 @@ with Racket.  For an introduction to Racket, see the @(other-manual '(lib "scrib
 @include-section["begin.scrbl"]
 @include-section["more.scrbl"]
 @include-section["types.scrbl"]
+@include-section["optimization.scrbl"]
 
 @;@section{How the Type System Works}
 

collects/typed-scheme/scribblings/ts-reference.scrbl

@@ -603,4 +603,17 @@ have the types ascribed to them; these types are converted to contracts and chec
   (define val 17))
 
 (fun val)]
+
+@section{Optimization in Typed Racket}
+
+Typed Racket provides a type-driven optimizer that rewrites well-typed
+programs to potentially make them faster. It should in no way make
+your programs slower or unsafe.
+
+Typed Racket's optimizer is not currently turned on by default. If you
+want to activate it, you must add the @racket[#:optimize] keyword when
+specifying the language of your program:
+
+@racketmod[typed/racket #:optimize]
+
 }