Add musicbrainz to plugins docs

Author: snejus

docs/plugins/index.rst

@@ -13,15 +13,19 @@ Using Plugins
 -------------
 
 To use one of the plugins included with beets (see the rest of this page for a
-list), just use the ``plugins`` option in your :doc:`config.yaml </reference/config>` file, like so::
+list), just use the ``plugins`` option in your :doc:`config.yaml </reference/config>` file:
+
+.. code-block:: sh
 
     plugins: inline convert web
 
 The value for ``plugins`` can be a space-separated list of plugin names or a
 YAML list like ``[foo, bar]``. You can see which plugins are currently enabled
 by typing ``beet version``.
 
-Each plugin has its own set of options that can be defined in a section bearing its name::
+Each plugin has its own set of options that can be defined in a section bearing its name:
+
+.. code-block:: yaml
 
     plugins: inline convert web
 
@@ -30,10 +34,11 @@ Each plugin has its own set of options that can be defined in a section bearing
 
 Some plugins have special dependencies that you'll need to install. The
 documentation page for each plugin will list them in the setup instructions.
-For some, you can use ``pip``'s "extras" feature to install the dependencies,
-like this::
+For some, you can use ``pip``'s "extras" feature to install the dependencies:
 
-    pip install beets[fetchart,lyrics,lastgenre]
+.. code-block:: sh
+
+    pip install "beets[fetchart,lyrics,lastgenre]"
 
 .. _metadata-source-plugin-configuration:
 
@@ -48,7 +53,9 @@ plugins share the following configuration option:
   Default: ``0.5``.
 
 For example, to equally consider matches from Discogs and MusicBrainz add the
-following to your configuration::
+following to your configuration:
+
+.. code-block:: yaml
 
     plugins: discogs
 
@@ -111,6 +118,7 @@ following to your configuration::
    missing
    mpdstats
    mpdupdate
+   musicbrainz
    parentwork
    permissions
    play
@@ -142,21 +150,26 @@ Autotagger Extensions
    Use acoustic fingerprinting to identify audio files with
    missing or incorrect metadata.
 
+:doc:`deezer <deezer>`
+   Search for releases in the `Deezer`_ database.
+
 :doc:`discogs <discogs>`
   Search for releases in the `Discogs`_ database.
 
+:doc:`fromfilename <fromfilename>`
+   Guess metadata for untagged tracks from their filenames.
+
+:doc:`musicbrainz <musicbrainz>`
+   Search for releases in the `MusicBrainz`_ database.
+
 :doc:`spotify <spotify>`
    Search for releases in the `Spotify`_ database.
 
-:doc:`deezer <deezer>`
-   Search for releases in the `Deezer`_ database.
-
-:doc:`fromfilename <fromfilename>`
-   Guess metadata for untagged tracks from their filenames.
 
-.. _Discogs: https://www.discogs.com/
+.. _Deezer: https://www.deezer.com
+.. _Discogs: https://www.discogs.com
+.. _MusicBrainz: https://www.musicbrainz.com
 .. _Spotify: https://www.spotify.com
-.. _Deezer: https://www.deezer.com/
 
 Metadata
 --------