Revert "doc correction for will-execute"

This reverts commit 52e7267273.

The change was for `will-try-execute`. And while the change
is a good idea, `will-try-execute` doesn't acually accept
the extra argument.

pkgs/racket-doc/scribblings/reference/memory.scrbl

@@ -190,10 +190,10 @@ call.  If no will is ready for immediate execution,
 @racket[will-execute] blocks until one is ready.}
 
 
-@defproc[(will-try-execute [executor any/c] [v any/c #f]) any]{
+@defproc[(will-try-execute [executor any/c]) any]{
 
 Like @racket[will-execute] if a will is ready for immediate
-execution. Otherwise, @racket[v] is returned.}
+execution. Otherwise, @racket[#f] is returned.}
 
 @;------------------------------------------------------------------------
 @section[#:tag "garbagecollection"]{Garbage Collection}