docs: Add a section on updating the local library
docs: Add a section on updating the local library

Fixes #1267

swak/mopidy,jodal/mopidy,bacontext/mopidy,vrs01/mopidy,diandiankan/mopidy,jmarsik/mopidy,swak/mopidy,mopidy/mopidy,hkariti/mopidy,adamcik/mopidy,tkem/mopidy,ZenithDK/mopidy,jmarsik/mopidy,jcass77/mopidy,jodal/mopidy,jcass77/mopidy,mokieyue/mopidy,tkem/mopidy,quartz55/mopidy,adamcik/mopidy,jodal/mopidy,bacontext/mopidy,jcass77/mopidy,ali/mopidy,kingosticks/mopidy,mopidy/mopidy,ZenithDK/mopidy,kingosticks/mopidy,quartz55/mopidy,ali/mopidy,bacontext/mopidy,vrs01/mopidy,hkariti/mopidy,quartz55/mopidy,swak/mopidy,jmarsik/mopidy,adamcik/mopidy,mokieyue/mopidy,vrs01/mopidy,swak/mopidy,hkariti/mopidy,tkem/mopidy,jmarsik/mopidy,ali/mopidy,ali/mopidy,mokieyue/mopidy,diandiankan/mopidy,bacontext/mopidy,quartz55/mopidy,mopidy/mopidy,pacificIT/mopidy,kingosticks/mopidy,pacificIT/mopidy,pacificIT/mopidy,mokieyue/mopidy,ZenithDK/mopidy,hkariti/mopidy,diandiankan/mopidy,diandiankan/mopidy,pacificIT/mopidy,tkem/mopidy,vrs01/mopidy,ZenithDK/mopidy