Readme update

Author: richard-li-sp

README.md

@@ -14,7 +14,10 @@ record which is necessary for the record to be indexed properly by
 elasticsearch.
 
 * If *@timestamp* field already exists, it will ensure the format is correct
-  by parse and convert to format '%Y-%m-%dT%H:%M:%S%z'.
+  by parse and convert to format '%Y-%m-%dT%H:%M:%S%z'. **As of version 0.2.4, it
+  will support epoch second / epoch millis format as a valid timestamp value. If
+  such value is detected, it will be converted to iso8601 format for easier
+  consumption of elasticsearch when dynamic mapping is used.**
 
 * If a field named *timestamp* or *time* or *syslog_timestamp* exists, it will
   parse that field and conver it to format '%Y-%m-%dT%H:%M:%S%z' then store it