SYSTEM_INFO type in the FieldOffset example should be a struct

[Perksey]

Summary

Alters the FieldOffsetAttribute example to demonstrate its usage on a struct instead of a class.

[gewarren]

@jkoritzinsky I think that the use of "class" may be intentional. Can you weigh in? If we approve this PR, we'll also need to update the intro text at https://docs.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.fieldoffsetattribute?view=netcore-3.1#examples.

[jkoritzinsky]

The text should say "struct or class" and the example can be either.

[Perksey]

Wow, TIL. It's probably better to use struct in the snippet as in most cases that's where StructLayout et al will be used, and I'm willing to update the text to reflect that both could be used if it's desirable?

[jkoritzinsky]

I would be OK updating the example to be a struct as long as the text is also updated.

[gewarren]

This example is also using it on a class.

https://docs.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.structlayoutattribute?view=netcore-3.1#examples