flowtop: man: Add how-to activate conntrack by modprobe

Add another tip how to activate conntrack mechanism by
loading required kernel modules via modprobe. This info
might be used to make these modules load automatically at startup.

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

flowtop.8

@@ -50,6 +50,14 @@ iptables -A INPUT -p tcp -m state --state ESTABLISHED -j ACCEPT
 .sp
 iptables -A OUTPUT -p tcp -m state --state NEW,ESTABLISHED -j ACCEPT
 .in -4
+.sp
+or by loading the following kernel modules:
+.sp
+.in +4
+modprobe nf_conntrack_ipv4
+.sp
+modprobe nf_conntrack_ipv6
+.in -4
 .PP
 To dump byte/packet counters flowtop enables the sysctl(8) parameter
 \[lq]net.netfilter.nf_conntrack_acct\[rq] via: