Revise documentation to state that mpg123 for music on hold is deprecated.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@42929 65c4cc65-6c06-0410-ace0-fbb531ad65f3

doc/mp3.txt

@@ -2,18 +2,12 @@
 ======================
 
 * MP3 Music On Hold
-Asterisk supports mp3 playback for music on hold via the mpg123
-program, available from www.mpg123.de.
+Use of the mpg123 for your music on hold is no longer recommended and is now
+officially deprecated.  You should now use one of the native formats for your
+music on hold selections.
 
-The latest release of mpg123 is mpg123 0.59r.
-The latest development release of mpg123 is mpg123 pre0.59s.
+However, if you still need to use mp3 as your music on hold format, a format
+driver for reading MP3 audio files is available in the asterisk-addons SVN
+repository on svn.digium.com or in the asterisk-addons release at
+ftp://ftp.digium.com/pub/telephony/asterisk/.
 
-Please use mpg123 0.59r.  Using mpg123 pre0.59s can/may/will result
-in crashes and/or unreliable playback.
-
-Running "make mpg123" in the Asterisk source directory will
-download and make the working version.
-
-* MP3 Format driver
-A format driver for reading MP3 audio files is available
-in the asterisk-addons CVS repository on cvs.digium.com