Update specs wording from Server 2012/Windows 8

[Tyler-H]

The recommended hardware specs in the IIS configuration documentation pages seem to max out at SQL Server 2012 (not even R2) and Windows 8. With 2012 R2 and 2016 out for years (not to mention Windows 10) and Server 2019 coming out in less than 6 months, the docs should probably be revised to make sure they don't recommend old versions or practices.