Add minimum requirements in readme.md

For those unaware, you can't just run this on any computer. It needs a CPU with AVX2 support and installed with a minimum version of ASP,NET Core 6.0 and FFmpeg 5.1.1 and presumably the latest version of Wine if running on Linux or macOS (I could not find any information on the minimum version of Wine that ASP.NET Core 6.0 runs on). You can hold this off until release.