Update awslogs driver batching documentation.

Before this change, the awslogs collectBatch and processEvent
function documentation still referenced the batchPublishFrequency
constant which was removed in favor of the configurable log stream
forceFlushInterval member.

Signed-off-by: Austin Vazquez <macedonv@amazon.com>

daemon/logger/awslogs/cloudwatchlogs.go

@@ -557,8 +557,10 @@ var newTicker = func(freq time.Duration) *time.Ticker {
 // pattern match is found, at which point the messages in the event buffer are
 // pushed to CloudWatch logs as a single log event.  Multiline messages are processed
 // according to the maximumBytesPerPut constraint, and the implementation only
-// allows for messages to be buffered for a maximum of 2*batchPublishFrequency
-// seconds.  When events are ready to be processed for submission to CloudWatch
+// allows for messages to be buffered for a maximum of 2*l.forceFlushInterval
+// seconds.  If no forceFlushInterval is specified for the log stream, then the default
+// of 5 seconds will be used resulting in a maximum of 10 seconds buffer time for multiline
+// messages. When events are ready to be processed for submission to CloudWatch
 // Logs, the processEvents method is called.  If a multiline pattern is not
 // configured, log events are submitted to the processEvents method immediately.
 func (l *logStream) collectBatch(created chan bool) {
@@ -623,8 +625,8 @@ func (l *logStream) collectBatch(created chan bool) {
 }
 
 // processEvent processes log events that are ready for submission to CloudWatch
-// logs.  Batching is performed on time- and size-bases.  Time-based batching
-// occurs at a 5 second interval (defined in the batchPublishFrequency const).
+// logs.  Batching is performed on time- and size-bases.  Time-based batching occurs
+// at the interval defined by awslogs-force-flush-interval-seconds (defaults to 5 seconds).
 // Size-based batching is performed on the maximum number of events per batch
 // (defined in maximumLogEventsPerPut) and the maximum number of total bytes in a
 // batch (defined in maximumBytesPerPut).  Log messages are split by the maximum