[skip ci]Add comment for GetCompactionState (#11599)

Signed-off-by: Nsunby <bingyi.sun@zilliz.com>
Co-authored-by: Nsunby <bingyi.sun@zilliz.com>

internal/datacoord/services.go

@@ -681,6 +681,7 @@ func (s *Server) ManualCompaction(ctx context.Context, req *milvuspb.ManualCompa
 	return resp, nil
 }
 
+// GetCompactionState gets the state of a compaction
 func (s *Server) GetCompactionState(ctx context.Context, req *milvuspb.GetCompactionStateRequest) (*milvuspb.GetCompactionStateResponse, error) {
 	log.Debug("receive get compaction state request", zap.Int64("compactionID", req.GetCompactionID()))
 	resp := &milvuspb.GetCompactionStateResponse{