update readme

README.md

@@ -19,10 +19,10 @@ The minimum required for enhanced emails to function is Icinga2.
 _Or you can apply notifications your own way, `enhance-mail-notification.py` and `enhance-mail-command.conf` contain the basics_
 
 ## Enhancements
-Grafana and Netbox have classes, which handle most of the work dealing with those services, in an attempt to keep the code for
-manage data from these services in one place. 
+Grafana and Netbox have classes, which handle most of the work dealing with those services, in an attempt to keep the code to
+manage data from these services in one place. These classes return values that are used in the content of the emails, they 
+should return empty strings or objects if no data is found.
 
-Enhancements to the existing external services or new services are encouraged to
-use classes for maintainability.
+Enhancements to the existing external services or new services are encouraged to use classes for maintainability.