docs: Fix minor doc issues found during review

- Adds autodoc for mopidy.audio.scan
- Updates ``file://`` to ``local:``
- Minor language fix.

docs/api/audio.rst

@@ -28,3 +28,10 @@ Audio listener
 
 .. autoclass:: mopidy.audio.AudioListener
     :members:
+
+
+Audio scanner
+=============
+
+.. autoclass:: mopidy.audio.scan.Scanner
+    :members:

docs/ext/local.rst

@@ -6,7 +6,7 @@ Mopidy-Local
 
 Extension for playing music from a local music archive.
 
-This backend handles URIs starting with ``file:``.
+This backend handles URIs starting with ``local:``.
 
 
 Known issues

docs/extensiondev.rst

@@ -353,7 +353,7 @@ Example backend
 
 If you want to extend Mopidy to support new music and playlist sources, you
 want to implement a backend. A backend does not have access to Mopidy's core
-API at all and got a bunch of interfaces to implement.
+API at all and have a bunch of interfaces to implement.
 
 The skeleton of a backend would look like this. See :ref:`backend-api` for more
 details.

mopidy/audio/scan.py

@@ -14,6 +14,15 @@ from mopidy.utils import path
 
 
 class Scanner(object):
+    """
+    Helper to get tags and other relevant info from URIs.
+
+    :param timeout: timeout for scanning a URI in ms
+    :type event: int
+    :param min_duration: minimum duration of scanned URI in ms, -1 for all.
+    :type event: int
+    """
+
     def __init__(self, timeout=1000, min_duration=100):
         self.timeout_ms = timeout
         self.min_duration_ms = min_duration
@@ -35,6 +44,13 @@ class Scanner(object):
         self.bus.set_flushing(True)
 
     def scan(self, uri):
+        """
+        Scan the given uri collecting relevant metadata.
+
+        :param uri: URI of the resource to scan.
+        :type event: string
+        :return: Dictionary of tags, duration, mtime and uri information.
+        """
         try:
             self._setup(uri)
             data = self._collect()