Fix wrong section name (smartplaylist => playlist)
Fix wrong section name (smartplaylist => playlist)

See https://discourse.beets.io/t/playlist-vs-smartplaylist-plugins/975/2
beetbox/beets,sampsyo/beets,jackwilsdon/beets,sampsyo/beets,SusannaMaria/beets,shamangeorge/beets,shamangeorge/beets,SusannaMaria/beets,SusannaMaria/beets,shamangeorge/beets,ibmibmibm/beets,ibmibmibm/beets,SusannaMaria/beets,sampsyo/beets,sampsyo/beets,beetbox/beets,ibmibmibm/beets,beetbox/beets,shamangeorge/beets,jackwilsdon/beets,beetbox/beets,ibmibmibm/beets,jackwilsdon/beets,jackwilsdon/beets