Correct batch-time-interval description in documentation

The description of the batch-time-interval parameter for the Gateway Sender in the Geode documentation states the following:
"Maximum amount of time, in ms, that can elapse before a batch is delivered."

Nevertheless, that is not completely true.

The number of ms that can elapse before a batch is delivered could be longer than what is configured in batch-time-interval in the case that the batch being created has not yet reached the value of max-batch-size and there are still events in the gateway sender's queue to be added to the batch. If that is the case, new events will keep being added to the batch without taking into account the value for batch-time-interval.

The batch-time-interval parameter is only used when the batch being filled has not reached the max-batch-size but there are no events in the queue. In that case, in order not to delay the delivery of the batch until there are events in the queue, this value is used to determine if the batch must be sent.