Update .NET Standard table (#10697)

* update ms.date * remove Windows rows

Author: mairaw

docs/standard/net-standard.md

@@ -3,7 +3,7 @@ title: .NET Standard
 description: Learn about .NET Standard, its versions and the .NET implementations that support it.
 author: mairaw
 ms.author: mairaw
-ms.date: 07/19/2018
+ms.date: 02/25/2019
 ms.technology: dotnet-standard
 ms.assetid: c044882c-af15-45f2-96d1-534557a5ee9b
 ---

includes/net-standard-table.md

@@ -7,9 +7,6 @@
 | Xamarin.Mac | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.8 |
 | Xamarin.Android | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | 8.0 |
 | Universal Windows Platform | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0.16299 | 10.0.16299 | 10.0.16299 |
-| Windows | 8.0 | 8.0 | 8.1 ||||||
-| Windows Phone | 8.1 | 8.1 | 8.1 ||||||
-| Windows Phone Silverlight | 8.0 ||||||||
 | Unity | 2018.1 | 2018.1 | 2018.1| 2018.1| 2018.1| 2018.1 | 2018.1 | 2018.1 |
 
 <sup>1 The versions listed for .NET Framework apply to .NET Core 2.0 SDK and later versions of the tooling. Older versions used a different mapping for .NET Standard 1.5 and higher. You can [download tooling for .NET Core tools for Visual Studio 2015](https://github.com/dotnet/core/blob/master/release-notes/download-archive.md) if you cannot upgrade to Visual Studio 2017.</sup>