Use nint type

[zgabi]

In the documentation you wrote that for example the SIZE_T should be (U)IntPtr in the C# code, which is understandable, but looks strange, for example: Kernel32.CopyMemory(dest, source, (IntPtr)length);

Please consider to add net5 target next to the existing ones, and use native integer types (nint, nuint) where the parameter is not a pointer. (For example by creating overlads to those methods)