CONTRIB: halog: Add help text for -s switch in halog program

It was not documented. May be backported to older releases.
diff --git a/contrib/halog/halog.c b/contrib/halog/halog.c
index cb815d8..fc336b4 100644
--- a/contrib/halog/halog.c
+++ b/contrib/halog/halog.c
@@ -180,6 +180,9 @@
 	       " -v                      invert the input filtering condition\n"
 	       " -q                      don't report errors/warnings\n"
 	       " -m <lines>              limit output to the first <lines> lines\n"
+               " -s <skip_n_fields>      skip n fields from the beginning of a line (default %d)\n"
+               "                         you can also use -n to start from earlier then field %d\n"
+               "\n"
 	       "Output filters - only one may be used at a time\n"
 	       " -c    only report the number of lines that would have been printed\n"
 	       " -pct  output connect and response times percentiles\n"
@@ -192,7 +195,8 @@
 	       "       -u : by URL, -uc : request count, -ue : error count\n"
 	       "       -ua : average response time, -ut : average total time\n"
 	       "       -uao, -uto: average times computed on valid ('OK') requests\n"
-	       "       -uba, -ubt: average bytes returned, total bytes returned\n"
+	       "       -uba, -ubt: average bytes returned, total bytes returned\n",
+               SOURCE_FIELD,SOURCE_FIELD
 	       );
 	exit(0);
 }