[docs/spl] Add documentation for new dest_regen option

docs/plugins/smartplaylist.rst

@@ -153,6 +153,11 @@ options are:
   ``yes``.
 - **playlist_dir**: Where to put the generated playlist files. Default: The
   current working directory (i.e., ``'.'``).
+- **dest_regen**: Regenerate the destination path as 'move' or 'convert'
+  commands would do. This operation will happen before ``relative_to`` and
+  ``prefix``. Helpful to generate playlists compatible with the ``convert``
+  plugin when items have been imported with the `-C -M` options.
+  Default: ``false``
 - **relative_to**: Generate paths in the playlist files relative to a base
   directory. If you intend to use this plugin to generate playlists for MPD,
   point this to your MPD music directory. Default: Use absolute paths.
@@ -167,7 +172,7 @@ options are:
   that will be written to the m3u file. Default: ``false``.
 - **uri_format**: Template with an ``$id`` placeholder used generate a playlist
   item URI, e.g. ``http://beets:8337/item/$id/file``. When this option is
-  specified, the local path-related options ``prefix``, ``relative_to``,
+  specified, the local path-related options ``dest_regen``, ``prefix``, ``relative_to``,
   ``forward_slash`` and ``urlencode`` are ignored.
 - **output**: Specify the playlist format: m3u|extm3u. Default ``m3u``.
 - **fields**: Specify the names of the additional item fields to export into the
@@ -176,6 +181,6 @@ options are:
   ``output`` option to ``extm3u``.
 
 For many configuration options, there is a corresponding CLI option, e.g.
-``--playlist-dir``, ``--relative-to``, ``--prefix``, ``--forward-slash``,
+``--playlist-dir``, ``--dest-regen``, ``--relative-to``, ``--prefix``, ``--forward-slash``,
 ``--urlencode``, ``--uri-format``, ``--output``, ``--pretend-paths``. CLI
 options take precedence over those specified within the configuration file.