rev-list-options: clarify the usage of --reverse

Users often wonder if the oldest or the newest n commits are shown
by `log -n --reverse`.  Clarify that --reverse kicks in only after
deciding which commits are to be shown to unconfuse them.

Reported-by: Ruediger Meier <sweet_f_a@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/rev-list-options.txt

@@ -638,8 +638,9 @@ avoid showing the commits from two parallel development track mixed
 together.
 
 --reverse::
-	Output the commits in reverse order.
-	Cannot be combined with `--walk-reflogs`.
+	Output the commits chosen to be shown (see Commit Limiting
+	section above) in reverse order. Cannot be combined with
+	`--walk-reflogs`.
 
 Object Traversal
 ~~~~~~~~~~~~~~~~