Add conceptual docs for Negotiate/Kerberos/NTLM auth for Linux-Windows interop

[davidsh]

See https://github.com/dotnet/corefx/issues/30203 for examples of what's needed for customers.

[mairaw]

Thanks @davidsh for filing the issue. Do you have a draft of this that we can help publish?

/cc @karelz

[karelz]

FYI: @wfurt

[dotnet-bot]

This issue has been closed as part of the issue backlog grooming process outlined in #22351.

That automated process may have closed some issues that should be addressed. If you think this is one of them, reopen it with a comment explaining why. Tag the @dotnet/docs team for visibility.

[MariusVolkhart]

I think documentation around this is still necessary. In enterprise deployments, this interop is still popular. @dotnet/docs

[MariusVolkhart]

@BillWagner please see ^