filer.meta.tail: add example to send metadata to elastic search

weed/command/filer_meta_tail.go

@@ -30,6 +30,8 @@ var cmdFilerMetaTail = &Command{
 	weed filer.meta.tail -timeAgo=30h | jq .
 	weed filer.meta.tail -timeAgo=30h | jq .eventNotification.newEntry.name
 
+	weed filer.meta.tail -timeAgo=30h -es=http://<elasticSearchServerHost>:<port> -es.index=seaweedfs
+
   `,
 }