not a showstopper but when using nuget in a project, it creates a packages.config file with this shape
You can always make simple xsd schema for 'packages.config' to get rid of this warning. To do this, create file named "packages.xsd":
Location of this file (two options)
packages.xsd across multiple projects, move it to the Visual Studio Schemas folder (the path may slightly differ, it's D:\Program Files (x86)\Microsoft Visual Studio 10.0\Xml\Schemas for me).Then, edit tag in packages.config file (add xmlns attribute):
Now the warning should disappear (even if packages.config file is open in Visual Studio).