Add changelog notes for recent PRs

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5cb5800..ac3b19f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,11 @@
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- Added CMake Find modules for aom, dav1d, rav1e (cryptomilk)
+
+### Changed
+- use right-most and bottom-most UV pixels in images with odd-dimensions (ledyba-z)
 
 ## [0.5.5] - 2020-02-13
 ### Added