Update index.rst
Corrects popularity service from spotify to deezer to match plugin
@@ -324,7 +324,7 @@ Here are a few of the plugins written by the beets community:
* `beets-originquery`_ augments MusicBrainz queries with locally-sourced data
to improve autotagger results.
-* `beets-popularity`_ fetches popularity values from Spotify.
+* `beets-popularity`_ fetches popularity values from Deezer.
* `beets-setlister`_ generate playlists from the setlists of a given artist.
