Updated C# and .NET docs supplement (markdown)

C#-and-.NET-docs-supplement.md

@@ -26,6 +26,12 @@ On (older versions of?) VS, `Condition` is ignored if placed on a property. Crea
 When `<Import/>`ing a `.props` file, `ProjectDir` is unset <!-- TODO only during property evaluation? --> (but `SolutionDir` *is* set, if applicable).
 Use `MSBuildProjectDirectory`. Note that the latter doesn't include a trailing slash.
 
+## NuGet resources are all for old CLI
+
+[up-to-date docs on MSDN](https://learn.microsoft.com/en-us/nuget/consume-packages/install-use-packages-dotnet-cli)
+
+`dotnet list BizHawk.sln package --outdated` lists outdated `<PackageReference/>`s
+
 ## `String.GetHashCode` stability
 
 The `GetHashCode` implementation for strings does not reflect the string's contents, and as such, the hash not stable between program instances.