Add VOD peak compression efficiency improvement

Bug: aomedia:3342
Change-Id: I6a73c550dab4768229eaf2f0d8b9de049df017db

CHANGELOG

diff --git a/CHANGELOG b/CHANGELOG
index b6afcce..b66891a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -20,6 +20,7 @@
     * RISC-V architecture support with gcc toolchain.
 
   - Compression Efficiency Improvements
+    * Peak compression efficiency in VOD setting is improved by 1%.
     * 0.7% - 2.2% RTC encoding BDrate gains for real time speed 8 to 10.
     * 15% RTC encoding BDrate gains for screen content speed 10.