[skip ci] Add comment for LoadCollectionTask (#9989)

Signed-off-by: Nxige-16 <xi.ge@zilliz.com>

internal/querycoord/task.go

@@ -238,6 +238,7 @@ func (bt *BaseTask) rollBack(ctx context.Context) []task {
 }
 
 //************************grpcTask***************************//
+// LoadCollectionTask will load all the data of this collection to query nodes
 type LoadCollectionTask struct {
 	*BaseTask
 	*querypb.LoadCollectionRequest