Use gh-pages for documentation

Consider using a different branch for documentation  

Proof of concept at https://github.com/kusl/unicorn-lib/tree/gh-pages 

Live demo: https://kusl.github.io/unicorn-lib/ 

One problem with this approach would be that as the project evolves, someone will need to update both the /doc in master and the documentation in the gh-pages branch. How would we solve this? Get rid of /doc in master? 
