The stubs were created by first generating the XML documentation from the source files, and then compiling a special Urho.dll that is a regular binary, not a PCL (as the Monodoc tools do not seem to run with PCL references).
The result was imported, and after this point, it is unlikely that it would be wise to update from the C++ sources.
The contents of this directory contain both original Xamarin content and content produced originally the Urho3D project and Cocos2D projects and have been adjusted to fit the C# bindings.