Clarify log/delete choice actions in files_antivirus

Fixes owncloud/files_antivirus#397

modules/admin_manual/pages/configuration/server/virus-scanner-support.adoc

@@ -251,7 +251,12 @@ image:configuration/server/anti-virus-message-socket-connection-problem.png[Conf
 
 === What To Do With Infected Files Found During Scans
 
-When infected files are detected during a scan, the app can take one of two actions:
+During an upload both of these actions are taken:
+
+* The upload is blocked.
+* The event is logged in both, owncloud server log and client / Web UI.
+
+During a background scan the app can take one of two actions:
 
 * **Log Only** Log the event.
 * **Delete file**: Delete the detected file.