Link .NET Foundation Code of Conduct

This addresses the pending policy violation.

This project currently links the Microsoft Code of Conduct, but it should link the .NET Foundation Code of Conduct. For more details, see [PR15](https://github.com/dotnet/org-policy/blob/main/doc/PR15.md).

CODE_OF_CONDUCT.md

@@ -1,9 +1,6 @@
-# Microsoft Open Source Code of Conduct
+# Code of Conduct
 
-This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/).
+This project has adopted the code of conduct defined by the Contributor Covenant
+to clarify expected behavior in our community.
 
-Resources:
-
-- [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/)
-- [Microsoft Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/)
-- Contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with questions or concerns
+For more information, see the [.NET Foundation Code of Conduct](https://dotnetfoundation.org/code-of-conduct).