Document "How to silence alerts/decisions for IPs that already have decisions"

[buixor]

cf. https://www.reddit.com/r/CrowdSec/comments/1gvby56/why_are_alertsdecisions_being_shown_for_something/

[LaurenceJJones]

Me and @blotus discussed this after daily so even with ActiveDecisionsCount helper you can never silence the alert, you can avoid making a decision but any alerts that get sent to lapi are documented and will be sent to the console no matter what.

From my own opinion if an alert is generated you would only want to silence a notification, not an alert as there is useful context information that you might want to know or explore EG: I have an application and somebody is exploiting an old vulnerability. Yes this would inflate the noise on your console account but we have no way to mark an alert to not to be sent currently within crowdsec.