doc edits

collects/scribblings/guide/apply.scrbl

@@ -122,15 +122,18 @@ are effectively @racket[cons]ed onto the argument list:
 (anti-sum '(1 2 3))
 ]
 
-The @racket[apply] function supports keyword arguments too:
+The @racket[apply] function accepts keyword arguments, too, and it
+passes them along to the called function:
 
 @racketblock[
 (apply go #:mode 'fast '("super.rkt"))
 (apply go '("super.rkt") #:mode 'fast)
 ]
 
-But since the keyword arguments are specified as usual, this form
-cannot be used with a list holding keywords and values.  For this, use
+Keywords that are included in @racket[apply]'s list argument do not
+count as keyword arguments for the called function; instead, all arguments in
+this list are treated as by-position arguments. To pass a list of
+keyword arguments to a function, use
 the @racket[keyword-apply] function, which accepts a function to apply
 and three lists. The first two lists are in parallel, where the first
 list contains keywords (sorted by @racket[keyword<]), and the second

collects/scribblings/reference/subprocess.scrbl

@@ -330,9 +330,10 @@ implement @racket[system].
 
 The resulting process writes to @racket[(current-output-port)], reads
 from @racket[(current-input-port)], and logs errors to
-@racket[(current-error-port)].  This means that processes usually
-interact with the user like regular code.  If you just want to gather
-the process's output to a string, for example, use:
+@racket[(current-error-port)]. To gather the process's non-error
+output to a string, for example, use @racket[with-output-to-string],
+which sets @racket[current-output-port] while calling the given
+function:
 
 @racketblock[
 (with-output-to-string (lambda () (system "date")))