[skip ci]Fix golint for SetRootCoord in distributed/querynode/service.go (#9814)

Signed-off-by: cai.zhang <cai.zhang@zilliz.com>

internal/distributed/querynode/service.go

@@ -259,6 +259,7 @@ func (s *Server) Stop() error {
 	return nil
 }
 
+// SetRootCoord sets the RootCoord's client for QueryNode component.
 func (s *Server) SetRootCoord(rootCoord types.RootCoord) error {
 	return s.querynode.SetRootCoord(rootCoord)
 }