Add Django-html support

[dfourie]

I have been wanting better support for the django-html language provided by djlint. It was a bit clunky to have to switch between languages when I was working on hyperscript.

This PR adds Django-html as a language that the syntax highlighting will be applied to. So it will play nicely with djlint for example, provided you set the language to Django-html

I also had to fix the build script as it appears the commits on master were incomplete.

Finally, I updated the readme with packaging instructions.