docs:fix syntax error in code sample.
docs:fix syntax error in code sample.

jodal/mopidy,mokieyue/mopidy,mopidy/mopidy,kingosticks/mopidy,jcass77/mopidy,adamcik/mopidy,ZenithDK/mopidy,ZenithDK/mopidy,tkem/mopidy,mopidy/mopidy,vrs01/mopidy,kingosticks/mopidy,adamcik/mopidy,tkem/mopidy,ZenithDK/mopidy,mokieyue/mopidy,mokieyue/mopidy,tkem/mopidy,vrs01/mopidy,tkem/mopidy,adamcik/mopidy,jcass77/mopidy,jodal/mopidy,jodal/mopidy,mopidy/mopidy,kingosticks/mopidy,ZenithDK/mopidy,vrs01/mopidy,jcass77/mopidy,vrs01/mopidy,mokieyue/mopidy