README.md: jookia.org -> www.jookia.org

README.md: Fix easy-rsa signature command

README.md: Use make instead of brmake ...

brmake looks nice, but it just hangs asking for a password.

README.md: Use /var/www/www.jookia.org as web directory ...

This isn't how I usually do things, but it makes more sense for the
README.

README.md: Actually fix certs.sh path now

README.md: 'utilities/certs.sh' > 'scripts/certs.sh'

README.md: Update to use certs.sh

README: "Buildroot repoistory" -> "external Buildroot repository"

README: Add instructions for building