Eliminate useless message about assuming zero delay when writing

a single-frame MNG.

diff --git a/ChangeLog b/ChangeLog
index a7f4da3..4afac36 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2010-07-27  6.6.3-2 Glenn Randers-Pehrson <glennrp@image...>
+  * Eliminate useless message about assuming zero delay when writing
+    a single-frame MNG.
+
 2010-07-25  6.6.3-1 Glenn Randers-Pehrson <glennrp@image...>
   * Don't "ping" a PNG image if it is embedded in a MNG.  Otherwise the
     reader tries to read MNG chunks from the interior of the embedded PNG,