Added code of conduct

Author: davidchesnut

README.md

@@ -161,3 +161,6 @@ Related tools
 ====
 
 - **Open XML Powertools**: This is available on [Github](https://github.com/OfficeDev/Open-Xml-PowerTools) and provides example code and guidance for implementing a wide range of Open XML scenarios.
+
+
+This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information, see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.