[skip ci] Add comment for printReplica (#9434)

Signed-off-by: Nbigsheeper <yihao.dai@zilliz.com>

internal/querynode/collection_replica.go

@@ -110,6 +110,7 @@ func (colReplica *collectionReplica) getSegmentsMemSize() int64 {
 	return memSize
 }
 
+// printReplica prints the collections, partitions and segments in the collectionReplica
 func (colReplica *collectionReplica) printReplica() {
 	colReplica.mu.Lock()
 	defer colReplica.mu.Unlock()