Update CHANGELOG for v1.4.0 (Indian Runner Duck) release

Change-Id: Id31b4da40c484aefc1236f5cc568171a9fd12af2

CHANGELOG

-2015-03-23 v1.4.0 "Indian Runner Duck"
+2015-04-03 v1.4.0 "Indian Runner Duck"
   This release includes significant improvements to the VP9 codec.
 
   - Upgrading:
@@ -18,6 +18,9 @@
     Fixes a VP9 bitstream issue in Profile 1. This only affected non-YUV 4:2:0
     files.
 
+  - Known Issues:
+    Frame Parallel decoding fails for segmented and non-420 files.
+
 2013-11-15 v1.3.0 "Forest"
   This release introduces the VP9 codec in a backward-compatible way.
   All existing users of VP8 can continue to use the library without