docs: Add link for Deezer music streaming service plugin
docs: Add link for Deezer music streaming service plugin

Link to https://github.com/rusty-dev/mopidy-deezer project.

adamcik/mopidy,adamcik/mopidy,jcass77/mopidy,mopidy/mopidy,jcass77/mopidy,kingosticks/mopidy,mopidy/mopidy,mopidy/mopidy,kingosticks/mopidy,adamcik/mopidy,jodal/mopidy,kingosticks/mopidy,jcass77/mopidy,jodal/mopidy,jodal/mopidy