Add comparison link against HEAD to CHANGELOG.md
Add comparison link against HEAD to CHANGELOG.md

Co-authored-by: Nikola Nikushev <448addf59670a7aa91a42839fcb64a7c1fe4fffa@hotmail.com>
bitmovin/bitmovin-player-ui,bitmovin/bitmovin-player-ui,bitmovin/bitmovin-player-ui,bitmovin/bitmovin-player-ui