Document workaround example for #492

The example is using an Icecast fallback stream that plays a silent MP3 file
when Mopidy sends the shutdown signal.

Tested and found working, however had minor issues with the client
(mpg123) playing the stream was getting out of sync when rapidly changing
songs.
Looking at the Icecast logs, it revealed that the switch between the mopidy and
the fallback stream happened immediately, so the issue is probably with the
client.

docs/config.rst

@@ -221,7 +221,7 @@ Streaming through SHOUTcast/Icecast
    Currently, Mopidy does not handle end-of-track vs end-of-stream signalling
    in GStreamer correctly. This causes the SHOUTcast stream to be disconnected
    at the end of each track, rendering it quite useless. For further details,
-   see :issue:`492`.
+   see :issue:`492`. You can also try the workaround_ mentioned below.
 
 If you want to play the audio on another computer than the one running Mopidy,
 you can stream the audio from Mopidy through an SHOUTcast or Icecast audio
@@ -237,17 +237,37 @@ server simultaneously. To use the SHOUTcast output, do the following:
 #. You might also need to change the ``shout2send`` default settings, run
    ``gst-inspect-0.10 shout2send`` to see the available settings. Most likely
    you want to change ``ip``, ``username``, ``password``, and ``mount``. For
-   example, to set the username and password, use:
+   example:
 
    .. code-block:: ini
 
        [audio]
-       output = lame ! shout2send username="alice" password="secret"
+       output = lame ! shout2send username="alice" password="secret" mount="mopidy"
 
 Other advanced setups are also possible for outputs. Basically, anything you
 can use with the ``gst-launch-0.10`` command can be plugged into
 :confval:`audio/output`.
 
+.. _workaround:
+
+**Workaround for end-of-track issues - fallback streams**
+
+By using a *fallback stream* playing silence, you can somewhat mitigate the
+signalling issues.
+
+Example Icecast configuration:
+
+.. code-block:: xml
+
+    <mount>
+      <mount-name>/mopidy</mount-name>
+      <fallback-mount>/silence.mp3</fallback-mount>
+      <fallback-override>1</fallback-override>
+    </mount>
+
+The ``silence.mp3`` file needs to be placed in the directory defined by
+``<webroot>...</webroot>``.
+
 
 New configuration values
 ------------------------