[skip ci] Add comment for showPartitions (#8864)

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

internal/querycoord/impl.go

@@ -212,6 +212,7 @@ func (qc *QueryCoord) ReleaseCollection(ctx context.Context, req *querypb.Releas
 	return status, nil
 }
 
+// ShowPartitions return all the partitions that have been loaded
 func (qc *QueryCoord) ShowPartitions(ctx context.Context, req *querypb.ShowPartitionsRequest) (*querypb.ShowPartitionsResponse, error) {
 	collectionID := req.CollectionID
 	log.Debug("show partitions start, ", zap.Int64("collectionID", collectionID), zap.Int64s("partitionIDs", req.PartitionIDs))