cherry-pick: fix docs describing handling of empty commits

Commit b27cfb0 (git-cherry-pick: Add keep-redundant-commits
option, 2012-04-20), added the --keep-redundant-commits
option, and switched the default behavior (without that
option) to silently ignore empty commits. Later, the second
half of that commit was reverted in ac2b0e8 (cherry-pick:
regression fix for empty commits, 2012-05-29), but the
documentation added for --keep-redundant-commits was never
updated to match. Let's do so now.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-cherry-pick.txt

@@ -131,7 +131,8 @@ effect to your index in a row.
 --keep-redundant-commits::
 	If a commit being cherry picked duplicates a commit already in the
 	current history, it will become empty.  By default these
-	redundant commits are ignored.  This option overrides that behavior and
+	redundant commits cause `cherry-pick` to stop so the user can
+	examine the commit. This option overrides that behavior and
 	creates an empty commit object.  Implies `--allow-empty`.
 
 --strategy=<strategy>::