Update CONTRIBUTING.md
Update CONTRIBUTING.md
FinalLevel/ExoPlayer,FinalLevel/ExoPlayer,Dysonics/ExoPlayer,reid-mcpherson/ExoPlayerDebug,Dysonics/ExoPlayer,ClubCom/AndroidExoPlayer,ClubCom/AndroidExoPlayer,Dysonics/ExoPlayer,ClubCom/AndroidExoPlayer,reid-mcpherson/ExoPlayerDebug,FinalLevel/ExoPlayer,reid-mcpherson/ExoPlayerDebug