Dear Maintainer,

When one of the HTML files of the Bind manual is opened in a browser, it's
displayed with very little formatting because the theme isn't found. The HTML
code references stylesheets and Javascript in a directory named "_static", but
those files are instead in a directory named "_static/_static".

All the files in /usr/share/doc/bind9-doc/arm/_static/_static should be moved
to /usr/share/doc/bind9-doc/arm/_static.