List the FFserver specific options under a "Main options" section, to

distinguish them from the generic common options.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22602 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

doc/ffserver-doc.texi

@@ -239,6 +239,8 @@ ffserver [options]
 
 @include fftools-common-opts.texi
 
+@section Main options
+
 @table @option
 @item -f @var{configfile}
 Use @file{configfile} instead of @file{/etc/ffserver.conf}.