SslStream is available in UWP 10.0.16299 but not addressed here

@taoyouh commented on [Thu Apr 11 2019](https://github.com/dotnet/dotnet-api-docs.zh-cn/issues/25)

Class SslStream and method SslStream.ShutdownAsync is available in UWP 10.0.16299 or higher. But it is not mentioned in the document.

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#### 文档详细信息

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* ID: 29aea839-74d6-6dfe-c54d-e1714a3b3367
* Version Independent ID: 9d8d412d-571e-c0df-439d-6adfbc334664
* Content: [SslStream.ShutdownAsync Method (System.Net.Security)](https://docs.microsoft.com/zh-cn/dotnet/api/system.net.security.sslstream.shutdownasync?view=netframework-4.7.2&viewFallbackFrom=dotnet-plat-ext-2.1#feedback)
* Content Source: [xml/System.Net.Security/SslStream.xml](https://github.com/dotnet/dotnet-api-docs.zh-cn/blob/live/xml/System.Net.Security/SslStream.xml)
* Product: **dotnet-api**
* Technology: **system.net**
* GitHub Login: @karelz
* Microsoft Alias: **ncldev**