Reformat the README and other docs to markdown

I saw Henrik present OpenNSA at the LHCONE meeting CERN and thought I might try a pull request that improves the docs committed to github.

This pull request moves the top level README to REAME.md which makes it more readable for people looking at the github page. I also reformatted the files in the docs directory without changing any of the content. To see the difference go browse: https://github.com/igable/opennsa

If you don't like these changes feel free to close this pull request.