remove redundant entry from manpage patch by (Nicolas Boos <nicolas.boos at wanadoo dot fr>)

Originally committed as revision 3305 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/ffmpeg-doc.texi

@@ -443,8 +443,6 @@ name and its parameters separated by spaces.
 @section Audio Options
 
 @table @option
-@item -ab bitrate         
-set audio bitrate (in kbit/s)
 @item -ar freq    
 set the audio sampling freq (default = 44100 Hz)
 @item -ab bitrate