issue2550774: Fix generating the website documentation - the COPYING.txt file needs to be symlinked into website/www/ so the documentation can be generated correctly - add website/www/COPYING.txt to the .hgignore file so the symlinked version does not get accidentally committed to the repository - the website documentation Makefile 'clean' removes the symlinks and the generated html to return things back to the original state, which is what should happen on a 'clean'