modify toc

Author: Yi Zhong

articles/iot-hub/TOC.md

@@ -144,14 +144,15 @@
 #### [Query language](iot-hub-devguide-query-language.md)
 #### [Quotas and throttling](iot-hub-devguide-quotas-throttling.md)
 #### [Pricing examples](iot-hub-devguide-pricing.md)
-#### [Device and service SDKs](iot-hub-devguide-sdks.md)
 #### [MQTT support](iot-hub-mqtt-support.md)
 #### [Glossary](iot-hub-devguide-glossary.md)
-### [Use the IoT device SDK for C](iot-hub-device-sdk-c-intro.md)
-#### [Use the IoTHubClient](iot-hub-device-sdk-c-iothubclient.md)
-#### [Use the serializer](iot-hub-device-sdk-c-serializer.md)
-### [Develop for constrained devices](iot-hub-devguide-develop-for-constrained-devices.md)
-### [Develop for mobile devices](iot-hub-how-to-develop-for-mobile-devices.md)
+### [Use device and service SDKs](iot-hub-devguide-sdks.md)
+#### [Use the IoT device SDK for C](iot-hub-device-sdk-c-intro.md)
+##### [Use the IoTHubClient](iot-hub-device-sdk-c-iothubclient.md)
+##### [Use the serializer](iot-hub-device-sdk-c-serializer.md)
+#### [Develop for constrained devices](iot-hub-devguide-develop-for-constrained-devices.md)
+#### [Develop for mobile devices](iot-hub-how-to-develop-for-mobile-devices.md)
+#### [Manage connectivity and reliable messaging](iot-hub-reliability-features-in-sdks.md)
 ### [Query Avro data from a hub route](iot-hub-query-avro-data.md)
 ### Send cloud-to-device messages
 #### [.NET](iot-hub-csharp-csharp-c2d.md)

articles/iot-hub/iot-hub-reliability-features-in-sdks.md

@@ -70,11 +70,11 @@ Three retry policies are provided:
 
    | SDK | SetRetryPolicy method | Policy implementations | Implementation guidance |
    |-----|----------------------|--|--|
-   |  C  | Not available        |  |  |
+   |  C/Python/iOS  | Not available        |  |  |
    | Java| Not available        |  |  |
    | .NET| [DeviceClient.SetRetryPolicy](/dotnet/api/microsoft.azure.devices.client.deviceclient.setretrypolicy?view=azure-dotnet#Microsoft_Azure_Devices_Client_DeviceClient_SetRetryPolicy_Microsoft_Azure_Devices_Client_IRetryPolicy) | **Default**: [ExponentialBackoff class](/dotnet/api/microsoft.azure.devices.client.exponentialbackoff?view=azure-dotnet)<BR>**Custom:** implement [IRetryPolicy interface](https://docs.microsoft.com/dotnet/api/microsoft.azure.devices.client.iretrypolicy?view=azure-dotnet)<BR>**No retry:** [NoRetry class](/dotnet/api/microsoft.azure.devices.client.noretry?view=azure-dotnet) | [C# example](#net-implementation-guidance) |
    | Node| [setRetryPolicy](/javascript/api/azure-iot-device/client?view=azure-iot-typescript-latest#azure_iot_device_Client_setRetryPolicy) | **Default**: [ExponentialBackoffWithJitter class](/javascript/api/azure-iot-common/exponentialbackoffwithjitter?view=azure-iot-typescript-latest)<BR>**Custom:** implement [RetryPolicy interface](/javascript/api/azure-iot-common/retrypolicy?view=azure-iot-typescript-latest)<BR>**No retry:** [NoRetry class](/javascript/api/azure-iot-common/noretry?view=azure-iot-typescript-latest) | [Node example](#node-implementation-guidance) |
-   | Python| Not available      |  |  |
+   
 
 Below are code examples that illustrates this flow.