Document "Happy Path" for EF Core based on Platform Version

[JeremyLikness]

Currently, the Entity Framework documentation shows EF Core version and target framework:

https://docs.microsoft.com/en-us/ef/core/what-is-new/

It may be implied that because EF Core 3.1 targets .NET Standard 2.0 that it is fully supported/"forward compatible" with .NET 5.0, but the team would recommend moving to EF Core 5.0 preview for users planning to move to .NET 5.0. The existing document should either be updated, or a new document created, that describes the recommendations for what version to use with which platform, along with links to any exist guidance for migration between versions.

[smitpatel]

Also mention somewhere that EF Core 5.0 is netstandard2.1 only

[ajcvickers]

@JeremyLikness Also see https://docs.microsoft.com/en-us/ef/core/platforms/