docs: Add link to libspotify docs
docs: Add link to libspotify docs

jodal/pyspotify,mopidy/pyspotify,mopidy/pyspotify,kotamat/pyspotify,kotamat/pyspotify,jodal/pyspotify,felix1m/pyspotify,kotamat/pyspotify,felix1m/pyspotify,felix1m/pyspotify,jodal/pyspotify