address the comment

Signed-off-by: Ryan Leung <[email protected]>

client/client.go

@@ -147,6 +147,11 @@ func NewClientWithContext(ctx context.Context, pdAddrs []string, security Securi
 	return c, nil
 }
 
+// GetConfigClient returns a config client through client.
+func (c *client) GetConfigClient() ConfigClient {
+	return &configClient{c.baseClient}
+}
+
 type deadline struct {
 	timer  <-chan time.Time
 	done   chan struct{}