Add contrib/pngminim/preader

based on contrib/gregbook/rpng2-x
diff --git a/CHANGES b/CHANGES
index 3674958..a16af78 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2134,6 +2134,8 @@
 version 1.4.0beta60 [May 18, 2009]
   Conditionally compile png_read_finish_row() which is not used by
     progressive readers.
+  Added contrib/pngminim/preader to demonstrate building minimal progressive
+    decoder, based on contrib/gregbook with embedded libpng and zlib.
 
 version 1.4.0betaN [future]
   Build shared libraries with -lz and sometimes -lm.