KAFKA-19102 Enhance the docs of group.coordinator.append.linger.ms (apache#19451)

Update the `group.coordinator.append.linger.ms` document, alterting
users to the potentail consequences of increasing value, It should
explain that increasing that value would improves write efficiency but
also increases response latency for requests.

Reviewers: TengYao Chi <[email protected]>, Chia-Ping Tsai
 <[email protected]>, PoAn Yang <[email protected]>

Author: m1a2st

group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupCoordinatorConfig.java

@@ -66,7 +66,9 @@ public class GroupCoordinatorConfig {
         Group.GroupType.CONSUMER.toString());
     public static final String GROUP_COORDINATOR_APPEND_LINGER_MS_CONFIG = "group.coordinator.append.linger.ms";
     public static final String GROUP_COORDINATOR_APPEND_LINGER_MS_DOC = "The duration in milliseconds that the coordinator will " +
-        "wait for writes to accumulate before flushing them to disk. Transactional writes are not accumulated.";
+        "wait for writes to accumulate before flushing them to disk. Increasing this value improves write efficiency and batch size, " +
+        "but also increases the response latency for requests, as the coordinator must wait for batches to be flushed to " +
+        "disk before completing request processing. Transactional writes are not accumulated.";
     public static final int GROUP_COORDINATOR_APPEND_LINGER_MS_DEFAULT = 5;
 
     public static final String GROUP_COORDINATOR_NUM_THREADS_CONFIG = "group.coordinator.threads";