Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -11,3 +11,9 @@ provided by the bot. You will only need to do this once across all repos using o
 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.
+
+## Code changes and 3rd-party libraries
+
+This sample is provided as guidance that represents how to apply princples outlined in the Well Architected Framework.
+The provided code, and guidance, should align with existing content in published Microsoft documentation.
+Usage of 3rd-party libraries should also be limited to those we recommend in published Microsot documentation.