docs: Document mopidy.local.translator

docs/modules/local.rst

@@ -6,4 +6,18 @@ For details on how to use Mopidy's local backend, see :ref:`ext-local`.
 
 .. automodule:: mopidy.local
     :synopsis: Local backend
+
+
+Local library API
+=================
+
+.. autoclass:: mopidy.local.Library
+   :members:
+
+
+Translation utils
+=================
+
+.. automodule:: mopidy.local.translator
+    :synopsis: Translators for local library extensions
     :members:

mopidy/local/translator.py

@@ -38,7 +38,8 @@ def path_to_file_uri(abspath):
 
 
 def path_to_local_track_uri(relpath):
-    """Convert path relative to media_dir to local track URI."""
+    """Convert path relative to :confval:`local/media_dir` to local track
+    URI."""
     if isinstance(relpath, compat.text_type):
         relpath = relpath.encode('utf-8')
     return b'local:track:%s' % urllib.quote(relpath)