Add documentation to make contribution easier.
Remove some co-maintainers who has no commit after 2012/10/30.
revert 53a9c95c86f0 for this file. "the changelog gets too cluttered with all the names; people read the changelog mostly because they want to know the changes."
less markup for README.rst, less emoticon for official.
suggested by birkenfeld, it's great honor to me :)