Adds note about `system*' output.

(Slightly revised by Eli.)

collects/scribblings/reference/subprocess.scrbl

@@ -320,22 +320,23 @@ real process ID).}
 
 Executes a Unix, Mac OS X, or Windows shell command synchronously
 (i.e., the call to @racket[system] does not return until the
-subprocess has ended). The @racket[command] argument is a string
-or byte string containing no nul characters. If the command succeeds, the return
-value is @racket[#t], @racket[#f] otherwise.
+subprocess has ended). The @racket[command] argument is a string or
+byte string containing no nul characters. If the command succeeds, the
+return value is @racket[#t], @racket[#f] otherwise.
 
 See also @racket[current-subprocess-custodian-mode] and
 @racket[subprocess-group-enabled], which affect the subprocess used to
-implement @racket[system].}
+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 show output to the screen and read from the keyboard by default.
-If you just want to gather the process's output to a string, for example, use:
+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:
 
 @racketblock[
 (with-output-to-string (lambda () (system "date")))
-]
+]}
 
 
 @defproc*[([(system* [command path-string?] [arg (or/c path? string? bytes?)] ...) boolean?]