utils: Add docstrings to all utils
utils: Add docstrings to all utils

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