Update README.md link to https (#8449)

Author: dibarbet

README.md

@@ -45,7 +45,7 @@ The source code to this extension is available on [https://github.com/dotnet/vsc
 
 This project has adopted the code of conduct defined by the [Contributor Covenant](http://contributor-covenant.org/)
 to clarify expected behavior in our community.
-For more information see the [.NET Foundation Code of Conduct](http://www.dotnetfoundation.org/code-of-conduct).
+For more information see the [.NET Foundation Code of Conduct](https://www.dotnetfoundation.org/code-of-conduct).
 
 ### Contribution License Agreement