Added 'Key AppEvent Properties' section to README.md

Author: trakerr-io

README.md

@@ -19,6 +19,25 @@ Some of these parameters are populated by default and others will need to be sup
 Since some of these parameters are common across all event's, the API has the option of setting these on the
 TrakerrClient instance (described towards the bottom) and offers a factory API for creating AppEvent's.
 
+### Key AppEvent Properties
+
+#### Log Level, Event Type and Classification
+* **Log Level** This enum specifies the logging level to be used for this event ('debug','info','warning','error' or 'fatal')
+* **Event Type** This defines the type of event or logger name. This is automatically set for errors.
+* **Classification** This is a user settable property that controls how the events are grouped. Defaults to 'Issue'. Set this to a different value to group this event in a different group.
+
+#### Event User, Event Session and Correlation ID
+* **Event User** This is the user that is associated with this event. This can be any user data or could be encrypted if privacy is required.
+* **Event Session** This is any session specific information associated with this event.
+* **Cross App Correlation ID** This is an additional ID that can be used for cross-application correlation of the same event.
+
+#### Operation Time
+* **Operation Time** This property in milliseconds measures the operation time for this specific event.
+
+#### Custom properties and segments
+In addition to the above, you can use custom properties and segments to send custom event, performance data. These
+can then be visualized in Trakerr's dashboards.
+
 ### Requirements
 - Java 1.7+
 - log4j 1.2 (if you want to use our log4j functionality)