The documentation in Spanish is in my Medium blog. https://medium.com/@DanielMonetelli/creando-una-limpia-librer%C3%ADa-de-estilos-para-xamarin-forms-v1-0-b02769f916ed
The documentation in English is in my personal blog https://danielmonetelli.azurewebsites.net/creating-a-clean-style-library-for-xamarin-forms-v1-0/
All my contributions are open source, with the purpose of learning and also give your granite of knowledge to the Xamarin community.