ps3-dump-bootloader: Minor help update

Signed-off-by: Geoff Levand <geoff@infradead.org>
diff --git a/ps3-dump-bootloader.in b/ps3-dump-bootloader.in
index a2eaf0f..7929118 100644
--- a/ps3-dump-bootloader.in
+++ b/ps3-dump-bootloader.in
@@ -25,7 +25,7 @@
 	echo "OPTIONS" >&2
 	echo "     -s, --sum" >&2
 	echo "             Compute the md5sum of the Other OS image and only print it to" >&2
-	echo "             stdout." >&2
+	echo "             stdout. Takes about 30 seconds to compute." >&2
 	echo "     -h, --help" >&2
 	echo "             Print a help message." >&2
 	echo "     -V, -version" >&2