The SDK packages published from this repo include a LICENSE.txt file, which contains the text of the MIT license:

However, https://docs.microsoft.com/en-us/nuget/reference/nuspec#license recommends that MIT-licensed packages should have <license type="expression">MIT</license> instead of referring to a file. In Directory.Build.targets, that would be <PackageLicenseExpression>MIT</PackageLicenseExpression>. I believe that would let the NuGet Gallery pages for Microsoft.Build.NoTargets and other packages display the text "MIT license", like the page for Microsoft.Extensions.Logging.Abstractions already does.

LICENSE.txt does contain a copyright notice that would not be covered by <license type="expression">MIT</license>:

However, almost the same copyright notice is already in the copyright element of the generated nuspec, so omitting the copyright notice from the license element seems OK. I believe it comes from the Copyright property that Directory.Build.targets sets: