[boost] Boost contributing tutorial (GitHub)

Hi, I prepared a tutorial about the contributing at GitHub/Boost describing how to create a Fork of a library, use it inside modular Boost and create a pull request. The tutorial presents examples for Boost.Geometry but could be extended to the other libraries. It has a form of a README of this repository: https://github.com/awulkiew/temp-contributing Would you be so kind and see if everything is ok wth it? In praticular I'd like to hear if this model is good for modular Boost in general? Regards, Adam