Document ffserver debug mode.

Originally committed as revision 13896 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/ffserver-doc.texi

@@ -255,6 +255,10 @@ Use @file{configfile} instead of @file{/etc/ffserver.conf}.
 Enable no-launch mode. This option disables all the Launch directives
 within the various <Stream> sections. FFserver will not launch any
 ffmpeg instance, so you will have to launch them manually.
+@item -d
+Enable debug mode. This option increases log verbosity, directs log
+messages to stderr and causes ffserver to run in the foreground
+rather than as a daemon.
 @end table
 @c man end