remove vs 2015 support

Author: danewalton-msft

articles/iot-hub/iot-hub-distributed-tracing.md

@@ -84,7 +84,7 @@ These instructions are for building the sample on Windows. For other environment
 
 ### Clone the source code and initialize
 
-1. Install ["Desktop development with C++" workload](/cpp/build/vscpp-step-0-installation?view=vs-2019&preserve-view=true) for Visual Studio 2019. Visual Studio 2017 and 2015 are also supported.
+1. Install ["Desktop development with C++" workload](/cpp/build/vscpp-step-0-installation?view=vs-2019&preserve-view=true) for Visual Studio 2019. Visual Studio 2017 is also supported.
 
 1. Install [CMake](https://cmake.org/). Make sure it is in your `PATH` by typing `cmake -version` from a command prompt.