Fixes#9219
@JunTaoLuo Dan calls out the implicit versioning "for 2.1 SDK or later;" however, we don't usually version the doc content by SDK release. We might need to say something for this update in the passage that I'm adding to the All topic (*aspnetcore/fundamentals/metapackage.md*) about which SDK version this applies to. I don't know if that's something that you would like to do or what version to call out.
I also remove the version from the samples. We also assume that devs are using the latest SDK with our samples.
* UE edit of Razor file compilation doc
* More edits
* Include .NET Framework csproj file
* More edits
* Apply more versioning moniker changes
* More cleanup
Luke Latham
Scott Addie