Update tutorials/libraries.md for MSBuild/csproj

[guardrex]

Developing Libraries with Cross Platform Tools

• https://docs.microsoft.com/en-us/dotnet/articles/core/tutorials/libraries
• https://github.com/dotnet/docs/blob/master/docs/core/tutorials/libraries.md

xref #1574

[mairaw]

@cartermp @terrajobst hey guys, wondering if any of you would have some bandwidth to update this guidance this month?

We should also move that .NET Standard table to an include file so that we only have to update one place when updating that table since the same info is also found at https://docs.microsoft.com/en-us/dotnet/articles/standard/library.

[cartermp]

I should be able to dedicate some time to this, yes.

[mairaw]

Assigning to you then @cartermp. #1693 is also related to this topic. Thanks!

[cartermp]

FYI, I'm midway through this. Lots of fundamental changes have to be made to this article, unfortunately. It's coming along.