azure-iot-sdk-c: use github for homepage

Many Buildroot users can not read Dutch. Although there is an English
version of this page, the github page looks more suitable as a link for
the software package itself, and the readme.md file is pretty
informative.

Cc: André Hentschel <nerv@dawncrow.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/azure-iot-sdk-c/Config.in

@@ -11,7 +11,7 @@ config BR2_PACKAGE_AZURE_IOT_SDK_C
 	  Microsoft Azure IoT Hub device SDK for C is used
 	  to connect devices running C code to Azure IoT Hub.
 
-	  https://docs.microsoft.com/nl-nl/azure/iot-hub/iot-hub-device-sdk-c-intro
+	  https://github.com/Azure/azure-iot-sdk-c
 
 comment "azure-iot-sdk-c needs a toolchain w/ C++ and NPTL"
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS_NPTL