dotnet/corefx ? reverse-engineered prompt

Please help me set up this repository as a simple archived project page that clearly tells people this code is no longer being developed here and that they should use dotnet runtime instead.

I want the main README to be polished and easy to understand, with a short explanation of why this repo exists, what it is for now, and a clear link to the new home. If it makes sense, add a small landing page or basic redirect style experience so visitors immediately know where to go next.

Keep it straightforward and professional, with wording that feels friendly to developers but still readable for anyone landing here by mistake. Look up current docs online if you need to make the message accurate.