Document missing EventSource field (#218)

* Document missing EventSource field

* Update LogMonitor/docs/README.md

Author: Saibamen

LogMonitor/docs/README.md

@@ -387,6 +387,7 @@ Each log source tracked by log monitor <em>(ETW, Log File, Events, and Process M
 <strong>Event Logs:</strong>
   - `Source`: The log source (Event Log)
   - `TimeStamp`: Time at which the event was generated
+  - `EventSource`: The source of an event
   - `EventID`: Unique identifier assigned to an individual event
   - `Severity`: A label that indicates the importance or criticality of an event
   - `Message`: The event message