We have a Xamarin Universal Library that you should know it. The idea is that the Xamarin community has one place for all the resources (Books, courses, e-books, jobs, etc) related to Xamarin. There are some interesting resources, you should take a look into it.
In the same way, If you can help maybe sending a PR, inviting other, giving a star or sharing to the communities you know. I don't know but it would be awesome if you can contribute.