fix: samples readme links were out-of-date

iothub/device/samples/readme.md

@@ -2,63 +2,73 @@
 This folder contains simple samples showing how to use the various features of Microsoft Azure IoT Hub service, from a device running C# code.
 
 ### [Device samples][device-samples]
-* [Message Sample][d-message-sample]
-* [Method Sample][d-method-sample]
-* [Twin Sample][d-twin-sample]
-* [File Upload Sample][d-file-upload-sample]
-* [Keys Rollover Sample][d-keys-rollover-sample]
-* [Import Export Devices Sample][d-import-export-devices-sample]
-* [Plug And Play Device Sample][d-pnp-sample]
-* [Xamarin Sample][d-xamarin-sample]
+
+- [Reconnection sample][d-message-sample]
+    - This sample illustrates how to write a device application to handle connection issues, connection-related exceptions, and how to manage the lifetime of the `DeviceClient`
+    - Includes sending messages and symmetric key failover
+- [Method sample][d-method-sample]
+- [Receive message sample][d-receive-message-sample]
+- [Twin sample][d-twin-sample]
+- [File upload sample][d-file-upload-sample]
+- [Import/export devices sample][d-import-export-devices-sample]
+- [Connect with X509 certificate sample][d-x509-cert-sample]
+- [Plug and Play device samples][d-pnp-sample]
+- [Xamarin sample][d-xamarin-sample]
 
 ### [Module samples][module-samples]
-* [Message Sample][m-message-sample]
-* [Twin Sample][m-twin-sample]
+
+- [Message sample][m-message-sample]
+- [Twin sample][m-twin-sample]
 
 ### Prerequisites
+
 In order to run the device samples on Linux or Windows, you will first need the following prerequisites:
-* [Setup your IoT hub][lnk-setup-iot-hub]
-* [Provision your device and get its credentials][lnk-manage-iot-device]
+
+- [Setup your IoT hub][lnk-setup-iot-hub]
+- [Provision your device and get its credentials][lnk-manage-iot-device]
 
 ### Setup environment
 
 The following prerequisite is the minimum requirement to build and run the samples. 
 
-Visual Studio is **not required** to run the samples.
+- Install the latest .NET Core from <https://dot.net>
 
-- Install the latest .NET Core from https://dot.net
+> Visual Studio is **not required** to run the samples.
 
 ### Get and run the samples
+
 You need to clone the repository or download the sample (the one you want to try) project's folder on your device.
 
-#### Build and run the samples:
+#### Build and run the samples
+
 1. Preparing the sample application:
    1. Set the following environment variables on the terminal from which you want to run the application.
 
-      * IOTHUB_DEVICE_CONNECTION_STRING
+      - IOTHUB_DEVICE_CONNECTION_STRING
 
-2. Building the sample application:
+1. Building the sample application:
 
-    To build the sample application using dotnet, from terminal navigate to the sample folder (where the .csproj file lives). Then execute the following command and check for build errors:
+To build the sample application using dotnet, from terminal navigate to the sample folder (where the .csproj file lives). Then execute the following command and check for build errors:
 
-    ```
-    dotnet build
-    ```
+```console
+dotnet build
+```
 
-3. Running the sample application:
+1. Running the sample application:
 
-	To run the sample application using dotnet, execute the following command.
+To run the sample application using dotnet, execute the following command.
 
-    ```
-    dotnet run
-    ```
+```console
+dotnet run
+```
 
 [device-samples]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device
-[d-message-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/MessageSample
+[d-message-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/DeviceReconnectionSample
+[d-receive-message-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/MessageReceiveSample
 [d-method-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/MethodSample
 [d-twin-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/TwinSample
 [d-file-upload-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/FileUploadSample
-[d-keys-rollover-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/KeysRolloverSample
+[d-x509-cert-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/X509DeviceCertWithChainSample
 [d-import-export-devices-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/ImportExportDevicesSample
 [d-pnp-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/PnpDeviceSamples
 [d-xamarin-sample]: https://github.com/Azure-Samples/azure-iot-samples-csharp/tree/master/iot-hub/Samples/device/XamarinSample