Doc fixes reported by Gary Baumgartner

The typo on 'redex.racket-lang.org' still remains.

Relevant to PR 12680

Merge to v5.3

collects/scribblings/drracket/keybindings.scrbl

@@ -254,7 +254,7 @@ s-exp framework/keybinding-lang
    (λ (ed evt)
      (when (is-a? ed text:basic<%>)
        (define fr (send ed get-top-level-window))
-       ;; note: fr could be #f
+       @code:comment{note: fr could be #f}
        (when fr (send fr command))))))
 
 (frame-key "t" execute-callback)

collects/scribblings/reference/class.scrbl

@@ -1260,7 +1260,7 @@ initialization variables can be mutated with @racket[set!].
 
 @subsection[#:tag "methodcalls"]{Methods}
 
-Method names within a class can only be used in the procedure position
+Method names used within a class can only be used in the procedure position
 of an application expression; any other use is a syntax error.
 
 To allow methods to be applied to lists of arguments, a method
@@ -1313,7 +1313,7 @@ Calls the method on @racket[obj] whose name matches
 @racket[kw-arg]s.}
 
 
-@defform/subs[(send* obj-expr msg ...)
+@defform/subs[(send* obj-expr msg ...+)
               ([msg (method-id arg ...)
                     (method-id arg ... . arg-list-expr)])]{