Simplify "ignore where" condition in the example config.

Refs #5795

doc/3-monitoring-basics.md

@@ -123,7 +123,7 @@ based on attribute identifiers for example `host_name` objects can be [applied](
       check_command = "ping4"
 
       assign where "generic-host" in host.templates
-      ignore where !host.address
+      ignore where host.address == ""
     }
 
 In this example the `ping4` service will be created as object for all hosts importing

etc/icinga2/conf.d/generic-host.conf

@@ -16,7 +16,7 @@ apply Service "ping4" {
   check_command = "ping4"
 
   assign where "generic-host" in host.templates
-  ignore where !host.address
+  ignore where host.address == ""
 }
 
 apply Service "ping6" {
@@ -25,7 +25,7 @@ apply Service "ping6" {
   check_command = "ping6"
 
   assign where "generic-host" in host.templates
-  ignore where !host.address6
+  ignore where host.address6 == ""
 }
 
 apply Notification "mail-icingaadmin" to Host {