README.md in fluent-plugin-elb-access-log-0.5.0 vs README.md in fluent-plugin-elb-access-log-0.6.0

@@ -51,9 +51,10 @@
   #filter elb_status_code:^2,timestamp:^2018
   #filter_operator and # or "or"
   #type_cast true
   #parse_request true
   #split_addr_port true
+  #file_filter REGEXP
 </source>
 ```
 
 ## Outout