specify max_events relation as well

Fixes #6343

config/logstash.yml

@@ -110,7 +110,8 @@
 # If using queue.type: persisted, the total capacity of the queue in number of bytes.
 # If you would like more unacked events to be buffered in Logstash, you can increase the 
 # capacity using this setting. Please make sure your disk drive has capacity greater than 
-# the size specified here.
+# the size specified here. If both max_bytes and max_events are specified, Logstash will pick 
+# whichever criteria is reached first
 # Default is 1024mb or 1gb
 #
 # queue.max_bytes: 1024mb