Update README.md with Compatibility Matrix

[FreddyDgh]

@lauxjpn @bubibubi Do you think a "Compatibility Matrix" like this would be helpful on the main README.md page? It seems like the largest share of questions arise from people wanting to use .NET Core or use the library with newer versions of EFCore.

[bubibubi]

Don't know. Actually that 3.x is next to be released could be helpful.

[lauxjpn]

I believe so. I think anything that helps people to get up and running is helpful.

Building upon that notion, we should probably include a small working console and a small working ASP.NET sample project (including the actual mdb file and some helpful comments including links, like the one for the Access Database Runtime Engine) that people can use as a working starting point, instead of figuring out all the EF Core, OleDb, Jet, runtime engine and processor architecture details by themselves.