During issue #2215 it was highlighted that the current behavior where
rules without a comment are ignored is confusing for several users.
This commit improves the documentation and adds a NOTE to the sample
config to clarify the behavior for new users.
The iptables plugin aims at monitoring bytes and packet counters
matching a given set of iptables rules.
Typically the user would set a dedicated monitoring chain into a given
iptables table, and add the rules to monitor to this chain. The plugin
will allow to focus on the counters for this particular table/chain.
closes#1471
Charles-Henri