Document how to export metrics and collect them

[renecannao]

For example using collectd or Diamond, together with Zabbix or Graphite

[amitbwy]

@renecannao is this done? Do we have some document that tells us the steps?

[bogdanr]

Here you have a plugin which works for Collectd:
https://github.com/mcrauwel/collectd-python-proxysql