Windows specific information in .NET Core

The docs for `System.IO.Path.GetTempPath()` claim it returns "The path to the temporary folder, ending with a backslash." This seems like it might need to be generalised for .NET Core, as well as the **Remarks** section.

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#### Document Details

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* ID: a81b4c67-7b0d-56c2-eccc-ef34b4ed2dca
* Version Independent ID: c05a5cc0-6c59-7954-eb46-e162419a5126
* Content: [Path.GetTempPath Method (System.IO)](https://docs.microsoft.com/en-us/dotnet/api/system.io.path.gettemppath?view=netcore-2.2)
* Content Source: [xml/System.IO/Path.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.IO/Path.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**