Netflow support version and flush_interval paramater

[hunterelectros]

Hello!

1. Flush_interval paramater - please explain what it means?
2. Does this exporter only support version 5 of the netflow protocol? If version 9 is not supported, are there plans to add such functionality?

[rkosegi]

1. flush_interval defines time for which is every metric entry kept alive. Stale entries are removed after given time to prevent memory exhaustion.

2. Only version 5. There are no plans for 9 or IPFIX, but PRs are always welcome