lnstat, nstat, ifstat: update man pages

New json option
diff --git a/man/man8/lnstat.8 b/man/man8/lnstat.8
index a76940b..699ddf4 100644
--- a/man/man8/lnstat.8
+++ b/man/man8/lnstat.8
@@ -33,6 +33,9 @@
 .B \-i, \-\-interval <intv>
 Set interval to 'intv' seconds.
+.B \-j, \-\-json
+Display results in JSON format
 .B \-k, \-\-keys k,k,k,...
 Display only keys specified.
diff --git a/man/man8/rtacct.8 b/man/man8/rtacct.8
index fb9afe8..c3ab03d 100644
--- a/man/man8/rtacct.8
+++ b/man/man8/rtacct.8
@@ -15,33 +15,35 @@
 are simple tools to monitor kernel snmp counters and network interface statistics.
--h -?
+.B \-h, \-\-help
 Print help
--v -V
+.B \-V, \-\-version
 Print version
+.B \-z, \-\-zero
 Dump zero counters too. By default they are not shown.
+.B \-r, \-\-reset
 Reset history.
+.B \-n, \-\-nooutput
 Do not display anything, only update history.
+.B \-a, \-\-ignore
 Dump absolute values of counters. The default is to calculate increments since the previous use.
+.B \-s, \-\-noupdate
 Do not update history, so that the next time you will see counters including values accumulated to the moment of this measurement too.
+.B \-j, \-\-json
+Display results in JSON format.
+.B \-d, \-\-interval <INTERVAL>
 Run in daemon mode collecting statistics. <INTERVAL> is interval between measurements in seconds.
 Time interval to average rates. Default value is 60 seconds.