external_monitoring callback hook is not documented

[etnt]

Hi,

I don't think this 'external_monitoring' callback hook is documented, or?
Should probably be documented in the system_monitor.app.src file.

system_monitor/src/system_monitor_events.erl

Line 68 in 1978c2b

case application:get_env(?APP, external_monitoring) of

Cheers, Tobbe

[mikpe]

PRs welcome. We're unfortunately short on bandwidth for GH right now.

[etnt]

Ok, will do.