doc/src/utilities.tex: what `open-output-port'?

	There seem to be a silly typo in `doc/src/utilities.tex',
	waiting for the following patch:

--- doc/src/utilities.tex~
+++ doc/src/utilities.tex
@@ -848,7 +848,7 @@
  \code{(current-row \cvar{port})} is not 0.
 
 \begin{example}
-(define p (open-output-port "/tmp/temp"))
+(define p (make-tracking-output-port (open-output-file "/tmp/temp")))
 (list (current-row p) (current-column p))
     \evalsto '(0 0)
 (display "012" p)

	BTW, shouldn't it be explained that the buffering behaviour on
	the resulting port may differ from the one of the original port,
	and one may have to use, e. g., `force-output' (e. g., when
	writing messages to a wrapped instance of the
	(current-error-port))?