Clarify if it moves files recursively

It's not motioned in this page whether all files in the subdirectories are also moved.

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#### Document Details

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* ID: 13a51385-4a3c-945c-3399-90b68435da51
* Version Independent ID: 78e60e8e-4be3-ff13-1016-ff9ec0eac9d3
* Content: [Directory.Move(String, String) Method (System.IO)](https://docs.microsoft.com/en-us/dotnet/api/system.io.directory.move?view=netframework-4.7.2)
* Content Source: [xml/System.IO/Directory.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.IO/Directory.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**