Update release notes
Update release notes

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=206921981

saki4510t/ExoPlayer,ened/ExoPlayer,amzn/exoplayer-amazon-port,androidx/media,androidx/media,google/ExoPlayer,stari4ek/ExoPlayer,ened/ExoPlayer,google/ExoPlayer,saki4510t/ExoPlayer,saki4510t/ExoPlayer,superbderrick/ExoPlayer,stari4ek/ExoPlayer,ened/ExoPlayer,androidx/media,google/ExoPlayer,superbderrick/ExoPlayer,superbderrick/ExoPlayer,stari4ek/ExoPlayer,amzn/exoplayer-amazon-port,amzn/exoplayer-amazon-port