Update doc for new core audio plugin features.

doc/user.xml

@@ -3169,6 +3169,28 @@ buffer_size: 16384</programlisting>
               </row>
               <row>
                 <entry>
+                  <varname>hog_device</varname>
+                  <parameter>yes|no</parameter>
+                </entry>
+                <entry>
+                  Hog the device. This means that it takes exclusive control of the audio
+                  output device it is playing through, and no other program can access it.
+                </entry>
+              </row>
+              <row>
+                <entry>
+                  <varname>sync_sample_rate</varname>
+                  <parameter>yes|no</parameter>
+                </entry>
+                <entry>
+                  Synchronize the sample rate. It will try to set the output device sample
+                  rate to the corresponding sample rate of the file playing. If the output
+                  device does not support the sample rate the track has, it will try to 
+                  select the best possible for each file.
+                </entry>
+              </row>
+              <row>
+                <entry>
                   <varname>channel_map</varname>
                   <parameter>SOURCE,SOURCE,...</parameter>
                 </entry>