[IPv6] Improve comment and update the doc (#1538)

* Improve comments in node_route_controller_test

pkg/agent/controller/noderoute/node_route_controller_test.go

@@ -124,7 +124,8 @@ func TestControllerWithDuplicatePodCIDR(t *testing.T) {
 		defer close(finishCh)
 
 		c.clientset.CoreV1().Nodes().Create(context.TODO(), node1, metav1.CreateOptions{})
-		// The 2nd argument is Any() because it is not safe to use pointer as key in a map. peerConfigs map[*net.IPNet]net.IP
+		// The 2nd argument is Any() because the argument is unpredictable when it uses pointer as the key of map.
+		// The argument type is map[*net.IPNet]net.IP.
 		c.ofClient.EXPECT().InstallNodeFlows("node1", gatewayMAC, gomock.Any(), nodeIP1, uint32(config.DefaultTunOFPort), uint32(0)).Times(1)
 		c.routeClient.EXPECT().AddRoutes(podCIDR, nodeIP1, podCIDRGateway).Times(1)
 		c.processNextWorkItem()
@@ -140,7 +141,8 @@ func TestControllerWithDuplicatePodCIDR(t *testing.T) {
 		c.processNextWorkItem()
 
 		// After node1 is deleted, routes and flows should be installed for node2 successfully.
-		// The 2nd argument is Any() because it is not safe to use pointer as key in a map. peerConfigs map[*net.IPNet]net.IP
+		// The 2nd argument is Any() because the argument is unpredictable when it uses pointer as the key of map.
+		// The argument type is map[*net.IPNet]net.IP.
 		c.ofClient.EXPECT().InstallNodeFlows("node2", gatewayMAC, gomock.Any(), nodeIP2, uint32(config.DefaultTunOFPort), uint32(0)).Times(1)
 		c.routeClient.EXPECT().AddRoutes(podCIDR, nodeIP2, podCIDRGateway).Times(1)
 		c.processNextWorkItem()